pod::Prima::Widget(3)

NAME
Prima::Widget - window management

DESCRIPTION
Prima::Widget is a descendant of Prima::Component, a class, especially crafted to reflect and govern properties of a system-dependent window, such as its position, hierarchy, outlook etc. Prima::Widget is mapped into the screen space as a rectangular area, with distinct boundaries, pointer and sometimes cursor, and a user-selectable input focus.

USAGE
Prima::Widget class and its descendants are used widely throughout the toolkit, and, indeed provide almost all its user interaction and input-output. The notification system, explained in Prima::Object, is employed in Prima::Widget heavily, providing the programmer with unified access to the system-generated events, that occur when the user moves windows, clicks the mouse, types the keyboard, etc. Descendants of Prima::Widget use the internal, the direct method of overriding the notifications, whereas end programs tend to use the toolkit widgets equipped with anonymous subroutines ( see Prima::Object for the details).

The class functionality is much more extensive comparing to the other built-in classes, and therefore the explanations are grouped in several topics.

Creation and destruction
The widget creation syntax is the same as for the other Prima objects:

   Prima::Widget-> create(
      name => 'Widget',
      size => [ 20, 10],
      onMouseClick => sub { print "click\n"; },
      owner => $owner,
   );

In the real life, a widget must be almost always explicitly told about its owner. The owner object is either a Prima::Widget descendant, in which case the widget is drawn inside its inferior, or the application object, and in the latter case a widget becomes top-level. This is the reason why the "insert" syntax is much more often used, as it is more illustrative and is more convenient for creating several widgets in one call ( see Prima::Object ).

   $owner-> insert( 'Prima::Widget',
      name => 'Widget',
      size => [ 20, 10],
      onMouseClick => sub { print "click\n"; },
   );

These two examples produce identical results.

As a descendant of Prima::Component, Prima::Widget sends "Create" notification when created ( more precisely, after its init stage is finished. See Prima::Object for details). This notification is called and processed within "create()" call. In addition, another notification "Setup" is sent after the widget is created. This message is posted, so it is called within "create()" but processed in the application event loop. This means that the execution time of "Setup" is uncertain, as it is with all posted messages; its delivery time is system-dependent, so its use must be considered with care.

After a widget is created, it is usually asked to render its content, provided that the widget is visible. This request is delivered by means of "Paint" notification.

When the life time of a widget is over, its method "destroy()" is called, often implicitly. If a widget gets destroyed because its owner also does, it is guaranteed that the children widgets will be destroyed first, and the owner afterwards. In such situation, widget can operate with a limited functionality both on itself and its owners ( see Prima::Object, Creation section ).

Graphic content
A widget can use two different ways for representing its graphic content to the user. The first method is event-driven, when the "Paint" notification arrives, notifying the widget that it must re-paint itself. The second is the 'direct' method, when the widget generates graphic output unconditionally.

  Event-driven rendering
A notification responsible for widget repainting is "Paint". It provides a single ( besides the widget itself ) parameter, an object, where the drawing is performed. In an event-driven call, it is always equals to the widget. However, if a custom mechanism should be used that directly calls, for example,

   $widget-> notify('Paint', $some_other_widget);

for whatever purpose, it is recommended ( not required, though ), to use this parameter, not the widget itself for painting and drawing calls.

The example of "Paint" callback is quite simple:

   Prima::Widget-> create(
       ...
       onPaint => sub {
          my ( $self, $canvas) = @_;
          $canvas-> clear;
          $canvas-> text_out("Clicked $self->{clicked} times", 10, 10);
       },
       onMouseClick => sub {
          $_[0]-> {clicked}++;
          $_[0]-> repaint;
       },
   );

The example uses several important features of the event-driven mechanism. First, no "begin_paint()"/"end_paint()" brackets are used within the callback. These are called implicitly. Second, when the custom refresh of the widget's graphic content is needed, no code like "notify(q(Paint))" is used - "repaint()" method is used instead. It must be noted, that the actual execution of "Paint" callbacks might or might not occur inside the "repaint()" call. This behavior is governed by the "::syncPaint" property. "repaint()" marks the whole widget's area to be refreshed, or invalidates the area. For the finer gradation of the area that should be repainted, "invalidate_rect()" and "validate_rect()" pair of functions is used. Thus,

  $x-> repaint()

code is a mere alias to

  $x-> invalidate_rect( 0, 0, $x-> size);

call. It must be realized, that the area, passed to "invalidate_rect()" only in its ideal ( but a quite often ) execution case will be pertained as a clipping rectangle when a widget executes its "Paint" notification. The user and system interactions can result in exposition of other parts of a widget ( like, moving windows over a widget ), and the resulting clipping rectangle can be different from the one that was passed to "invalidate_rect()". Moreover, the clipping rectangle can become empty as the result of these influences, and the notification will not be called at all.

Invalid rectangle is presented differently inside and outside the drawing mode. The first, returned by "::clipRect", employs inclusive-inclusive coordinates, whereas "invalidate_rect()", "validate_rect()" and "get_invalid_rect()" - inclusive-exclusive coordinates. The ideal case exemplifies the above said:

   $x-> onPaint( sub {
      my @c = $_[0]-> clipRect;
      print "clip rect:@c\n";
   });
   $x-> invalidate_rect( 10, 10, 20, 20);
   ...
   clip rect: 10 10 19 19

As noted above, "::clipRect" property is set to the clipping rectangle of the widget area that is needed to be refreshed, and an event handler code can take advantage of this information, increasing the efficiency of the painting procedure.

Further assignments of "::clipRect" property do not make possible over-painting on the screen area that lies outside the original clipping region. This is also valid for all paint operations, however since the original clipping rectangle is the full area of a canvas, this rule is implicit and unnecessary, because whatever large the clipping rectangle is, drawing and painting cannot be performed outside the physical boundaries of the canvas.

  Direct rendering
The direct rendering, contrary to the event-driven, is initiated by the program, not by the system. If a programmer wishes to paint over a widget immediately, then "begin_paint()" is called, and, if successful, the part of the screen occupied by the widget is accessible to the drawing and painting routines.

This method is useful, for example, for graphic demonstration programs, that draw continuously without any input. Another field is the screen drawing, which is performed with Prima::Application class, that does not have "Paint" notification. Application's graphic canvas represents the whole screen, allowing over-drawing the graphic content of other programs.

The event-driven rendering method adds implicit "begin_paint()"/"end_paint()" brackets ( plus some system-dependent actions ) and is a convenience version of the direct rendering. Sometimes, however, the changes needed to be made to a widget's graphic context are so insignificant, so the direct rendering method is preferable, because of the cleaner and terser code. As an example might serve a simple progress bar, that draws a simple colored bar. The event-driven code would be ( in short, omitting many details ) as such:

   $bar = Widget-> create(
     width => 100,
     onPaint => sub {
        my ( $self, $canvas) = @_;
        $canvas-> color( cl::Blue);
        $canvas-> bar( 0, 0, $self-> {progress}, $self-> height);
        $canvas-> color( cl::Back);
        $canvas-> bar( $self-> {progress}, 0, $self-> size);
     },
   );
   ...
   $bar-> {progress} += 10;
   $bar-> repaint;
   # or, more efficiently, ( but clumsier )
   # $bar-> invalidate_rect( $bar->{progress}-10, 0,
   #                 $bar->{progress}, $bar-> height);

And the direct driven:

   $bar = Widget-> create( width => 100 );
   ...
   $bar-> begin_paint;
   $bar-> color( cl::Blue);
   $bar-> bar( $progress, 0, $progress + 10, $bar-> height);
   $bar-> end_paint;
   $progress += 10;

The pros and contras are obvious: the event-driven rendered widget correctly represents the status after an eventual repaint, for example when the user sweeps a window over the progress bar widget. The direct method cannot be that smart, but if the status bar is an insignificant part of the program, the trade-off of the functionality in favor to the code simplicity might be preferred.

Both methods can be effectively disabled using the paint locking mechanism. The "lock()" and "unlock()" methods can be called several times, stacking the requests. This feature is useful because many properties implicitly call "repaint()", and if several of these properties activate in a row, the unnecessary redrawing of the widget can be avoided. The drawback is that the last "unlock()" call triggers "repaint()" unconditionally.

Geometry

  Basic properties
A widget always has its position and size determined, even if it is not visible on the screen. Prima::Widget provides several properties with overlapping functionality, that govern the geometry of a widget. The base properties are "::origin" and "::size", and the derived are "::left", "::bottom", "::right", "::top", "::width", "::height" and "::rect". "::origin" and "::size" operate with two integers, "::rect" with four, others with one integer value.

As the Prima toolkit coordinate space begins in the lower bottom corner, the combination of "::left" and "::bottom" is same as "::origin", and combination of "::left", "::bottom", "::right" and "::top" - same as "::rect".

When a widget is moved or resized, correspondingly two notifications occur: "Move" and "Size". The parameters to both are old and new position and size. The notifications occur irrespectable to whether the geometry change was issued by the program itself or by the user.

  Implicit size regulations
Concerning the size of a widget, two additional two-integer properties exist, "::sizeMin" and "::sizeMax", that constrain the extension of a widget in their boundaries. The direct call that assigns values to the size properties that lie outside "::sizeMin" and "::sizeMax" boundaries, will fail - the widget extension will be adjusted to the boundary values, not to the specified ones.

Change to widget's position and size can occur not only by an explicit call to one of the geometry properties. The toolkit contains implicit rules, that can move and resize a widget corresponding to the flags, given to the "::growMode" property. The exact meaning of the "gm::XXX" flags is not given here ( see description to "::growMode" in API section ), but in short, it is possible with simple means to maintain widget's size and position regarding its owner, when the latter is resized. By default, and the default behavior corresponds to "::growMode" 0, widget does not change neither its size nor position when its owner is resized. It stays always in 'the left bottom corner'. When, for example, a widget is expected to stay in 'the right bottom corner', or 'the left top corner', the "gm::GrowLoX" and "gm::GrowLoY" values must be used, correspondingly. When a widget is expected to cover, for example, its owner's lower part and change its width in accord with the owner's, ( a horizontal scroll bar in an editor window is the example), the "gm::GrowHiX" value must be used.

When this implicit size change does occur, the "::sizeMin" and "::sizeMax" do take their part as well - they still do not allow the widget's size excess their boundaries. However, this algorithm derives a problem, that is illustrated by the following setup. Imagine a widget with size-dependent "::growMode" ( with "gm::GrowHiX" or "gm::GrowHiY" bits set ) that must maintain certain relation between the owner's size and its own. If the implicit size change would be dependent on the actual widget size, derived as a result from the previous implicit size action, then its size (and probably position) will be incorrect after an attempt is made to change the widget's size to values outside the size boundaries.

Example: child widget has width 100, growMode set to "gm::GrowHiX" and sizeMin set to (95, 95). Its owner has width 200. If the owner widget changes gradually its width from 200 to 190 and then back, the following width table emerges:

                    Owner        Child
  Initial state      200           100
  Shrink             195   -5       95
  Shrink             190   -5       95 - as it can not be less than 95.
  Grow               195   +5      100
  Grow               200   +5      105

That effect would exist if the differential-size algorithm would be implemented, - the owner changes width by 5, and the child does the same. The situation is fixed by introducing the virtual size term. The "::size" property is derived from virtual size, and as "::size" cannot exceed the size boundaries, virtual size can. It can even accept the negative values. With this intermediate stage added, the correct picture occurs:

                    Owner        Child's       Child's
                                 virtual width  width
  Initial state      200           100           100
  Shrink             195   -5       95            95
  Shrink             190   -5       90            95
  Grow               195   +5       95            95
  Grow               200   +5      100           100

Strictly speaking, the virtual size must be declared a read-only property, but currently it is implemented as a "get_virtual_size()" function, and it is planned to fix this discrepancy between the document and the implementation in favor of the property syntax.

  Geometry managers
The concept of geometry managers is imported from Tk, which in turn is a port of Tcl-Tk. The idea behind it is that a widget size and position is governed by one of the managers, which operate depending on the specific options given to the widget. The selection is operated by "::geometry" property, and is one of "gt::XXX" constants. The native ( and the default ) geometry manager is the described above grow-mode algorithm ( "gt::GrowMode" ). The currently implemented Tk managers are packer ( "gt::Pack" ) and placer ( "gt::Place"). Each has its own set of options and methods, and their manuals are provided separately in Prima::Widget::pack and Prima::Widget::place ( the manpages are also imported from Tk ).

Another concept that comes along with geometry managers is the 'geometry request size'. It is realized as a two-integer property "::geomSize", which reflects the size selected by some intrinsic widget knowledge, and the idea is that "::geomSize" it is merely a request to a geometry manager, whereas the latter changes "::size" accordingly. For example, a button might set its 'intrinsic' width in accord with the width of text string displayed in it. If the default width for such a button is not overridden, it is assigned with such a width. By default, under "gt::GrowMode" geometry manager, setting "::geomSize" ( and its two semi-alias properties "::geomWidth" and "::geomHeight" ) also changes the actual widget size.Moreover, when the size is passed to the Widget initialization code, "::size" properties are used to initialize "::geomSize". Such design minimizes the confusion between the two properties, and also minimizes the direct usage of "::geomSize", limiting it for selecting advisory size in widget internal code.

The geometry request size is useless under "gt::GrowMode" geometry manager, but Tk managers use it extensively.

  Relative coordinates
Another geometry issue, or rather a programming technique must be mentioned - the relative coordinates. It is the well-known problem, when a dialog window, developed with one font looks garbled on another system with another font. The relative coordinates solve the problem; the solution provides the "::designScale" two-integer property, the width and height of the font, that was used when the dialog window was designed. With this property supplied, the position and size supplied when a widget is actually created, are transformed in proportion between the designed and the actual font metrics.

The relative coordinates can be used only when passing the geometry properties values, and only before the creation stage, before a widget is created, because the scaling calculations perform in Prima::Widget::"profile_check_in()" method.

In order to employ the relative coordinates scheme, the owner ( or the dialog ) widget must set its "::designScale" to the font metrics and "::scaleChildren" property to 1. Widgets, created with owner that meets these requirements, participate in the relative coordinates scheme. If a widget must be excluded from the relative geometry applications, either the owner's property "::scaleChildren" must be set to 0, or the widget's "::designScale" must be set to "undef". As the default "::designScale" value is "undef", no default implicit relative geometry schemes are applied.

The "::designScale" property is auto-inherited; its value is copied to the children widgets, unless the explicit "::designScale" was given during the widget's creation. This is used when such a child widget serves as an owner for some other grand-children widgets; the inheritance scheme allows the grand- ( grand- etc ) children to participate in the relative geometry scheme.

Note: it is advised to test such applications with the Prima::Stress module, which assigns a random font as the default, so the testing phase does not involve tweaking of the system settings.

Z-order
In case when two widgets overlap, one of these is drawn in full, whereas the another only partly. Prima::Widget provides management of the Z-axis ordering, but since Z-ordering paradigm can hardly be fit into the properties scheme, the toolkit uses methods instead.

A widget can use four query methods: "first()", "last()", "next()", and "prev()". These return, correspondingly, the first and the last widgets in Z-order stack, and the direct neighbors of a widget ( $widget-> next-> prev always equals to the $widget itself, given that $widget-> next exists ).

The last widget is the topmost one, the one that is drawn fully. The first is the most obscured one, given that all the widgets overlap.

Z-order can also be changed at runtime ( but not during widget's creation). There are three methods: "bring_to_front()", that sets the widget last in the order, making it topmost, "send_to_back()", that does the reverse, and "insert_behind()", that sets a widget behind the another widget, passed as an argument.

Changes to Z-order trigger "ZOrderChanged" notification.

Parent-child relationship
By default, if a widget is a child to a widget or window, it maintains two features: it is clipped by its owner's boundaries and is moved together as the owner widget moves. It is said also that a child is inferior to its parent. However, a widget without a parent still does have a valid owner. Instead of implementing parent property, the "::clipOwner" property was devised. It is 1 by default, and if it is 1, then owner of a widget is its parent, at the same time. However, when it is 0, many things change. The widget is neither clipped nor moved together with its parent. The widget become parentless, or, more strictly speaking, the screen becomes its parent. Moreover, the widget's origin offset is calculated then not from the owner's coordinates but from the screen, and mouse events in the widget do not transgress implicitly to the owner's top-level window eventual decorations.

The same results are produced if a widget is inserted in the application object, which does not have screen visualization. A widget that belongs to the application object, can not reset its "::clipOwner" value to 1.

The "::clipOwner" property opens a possibility for the toolkit widgets to live inside other programs' windows. If the "::parentHandle" is changed from its default "undef" value to a valid system window handle, the widget becomes child to this window, which can belong to any application residing on the same display. This option is dangerous, however: normally widgets never get destroyed by no reason. A top-level window is never destroyed before its "Close" notification grants the destruction. The case with "::parentHandle" is special, because a widget, inserted into an alien application, must be prepared to be destroyed at any moment. It is recommended to use prior knowledge about such the application, and, even better, use one or another inter-process communication scheme to interact with it.

A widget does not need to undertake anything special to become an 'owner'. Any widget, that was set in "::owner" property on any other widget, becomes owner automatically. Its "get_widgets()" method returns non-empty widget list. "get_widgets()" serves same purpose as Prima::Component::"get_components()", but returns only Prima::Widget descendants.

A widget can change its owner at any moment. The "::owner" property is both readable and writable, and if a widget is visible during the owner change, it is immediately appeared under different coordinates and different clipping condition after the property change, given that its "::clipOwner" is set to 1.

Visibility
A widget is visible by default. Visible means that it is shown on the screen if it is not shadowed by other widgets or windows. The visibility is governed by the "::visible" property, and its two convenience aliases, "show()" and "hide()".

When a widget is invisible, its geometry is not discarded; the widget pertains its position and size, and is subject to all previously discussed implicit sizing issues. When change to "::visible" property is made, the screen is not updated immediately, but in the next event loop invocation, because uncovering of the underlying area of a hidden widget, and repainting of a new-shown widget both depend onto the event-driven rendering functionality. If the graphic content must be updated, "update_view()" must be called, but there's a problem. It is obvious that if a widget is shown, the only content to be updated is its own. When a widget becomes hidden, it may uncover more than one widget, depending on the geometry, so it is unclear what widgets must be updated. For the practical reasons, it is enough to get one event loop passed, by calling "yield()" method of the $::application object. The other notifications may pass here as well, however.

There are other kinds of visibility. A widget might be visible, but one of its owners might not. Or, a widget and its owners might be visible, but they might be over-shadowed by the other windows. These conditions are returned by "showing()" and "exposed()" functions. These return boolean values corresponding to the condition described. So, if a widget is 'exposed', it is 'showing' and 'visible'; "exposed()" returns always 0 if a widget is either not 'showing' or not 'visible'. If a widget is 'showing', then it is always 'visible'. "showing()" returns always 0 if a widget is invisible.

Visibility changes trigger "Hide" and "Show" notifications.

Focus
One of the key points of any GUI is that only one window at a time can possess a focus. The widget is focused, if the user's keyboard input is directed to it. The toolkit adds another layer in the focusing scheme, as often window managers do, highlighting the decorations of a top-level window over a window with the input focus.

Prima::Widget property "::focused" governs the focused state of a widget. It is sometimes too powerful to be used. Its more often substitutes, "::selected" and "::current" properties provide more respect to widget hierarchy.

"::selected" property sets focus to a widget if it is allowed to be focused, by the usage of the "::selectable" property. With this granted, the focus is passed to the widget or to the one of its ( grand-) children. So to say, when 'selecting' a window with a text field by clicking on a window, one does not expect the window to be focused, but the text field. To achieve this goal and reduce unnecessary coding, the "::current" property is introduced. With all equal conditions, a widget that is 'current' gets precedence in getting selected over widgets that are not 'current'.

De-selecting, in its turn, leaves the system in such a state when no window has input focus. There are two convenience shortcuts "select()" and "deselect()" defined, aliased to selected(1) and selected(0), correspondingly.

As within the GUI space, there can be only one 'focused' widget, so within the single widget space, there can be only one 'current' widget. A widget can be marked as a current by calling "::current" ( or, identically, "::currentWidget" on the owner widget ). The reassignments are performed automatically when a widget is focused. The reverse is also true: if a widget is explicitly marked as 'current', and belongs to the widget tree with the focus in one of its widgets, then the focus passed to the 'current' widget, or down to hierarchy if it is not selectable.

These relations between current widget pointer and focus allow the toolkit easily implement the focusing hierarchy. The focused widget is always on the top of the chain of its owner widgets, each of whose is a 'current' widget. If, for example, a window that contains a widget that contains a focused button, become un-focused, and then user selects the window again, then the button will become focused automatically.

Changes to focus produce "Enter" and "Leave" notifications.

Below discussed mouse- and keyboard- driven focusing schemes. Note that all of these work via "::selected", and do not focus the widgets with "::selectable" property set to 0.

  Mouse-aided focusing
Typically, when the user clicks the left mouse button on a widget, the latter becomes focused. One can note that not all widgets become focused after the mouse click - scroll bars are the examples. Another kind of behavior is the described above window with the text field - clicking mouse on a window focuses a text field.

Prima::Widget has the "::selectingButtons" property, a combination of mb::XXX ( mouse buttons ) flags. If the bits corresponding to the buttons are set, then click of this button will automatically call ::selected(1) ( not ::focused(1) ).

Another boolean property, "::firstClick" determines the behavior when the mouse button action is up to focus a widget, but the widget's top-level window is not active. The default value of "::firstClick" is 1, but if set otherwise, the user must click twice to a widget to get it focused. The property does not influence anything if the top-level window was already active when the click event occured.

Due to some vendor-specific GUI designs, it is hardly possibly to force selection of one top-level window when the click was on the another. The window manager or the OS can interfere, although this does not always happen, and produce different results on different platforms. Since the primary goal of the toolkit is portability, such functionality must be considered with care. Moreover, when the user selects a window by clicking not on the toolkit-created widgets, but on the top-level window decorations, it is not possible to discern the case from any other kind of focusing.

  Keyboard focusing
The native way to navigate between the toolkit widgets are tab- and arrow- navigation. The tab ( and its reverse, shift-tab ) key combinations circulate the focus between the widgets in same top-level group ( but not inside the same owner widget group ). The arrow keys, if the focused widget is not interested in these keystrokes, move the focus in the specified direction, if it is possible. The methods that provide the navigations are available and called "next_tab()" and "next_positional()", correspondingly ( see API for the details).

When "next_positional()" operates with the geometry of the widgets, "next_tab()" uses the "::tabStop" and "::tabOrder" properties. "::tabStop", the boolean property, set to 1 by default, tells if a widget is willing to participate in tab-aided focus circulation. If it doesn't, "next_tab()" never uses it in its iterations. "::tabOrder" value is an integer, unique within the sibling widgets ( sharing same owner ) list, and is used as simple tag when the next tab-focus candidate is picked up. The default "::tabOrder" value is -1, which changes automatically after widget creation to a unique value.

User input
The toolkit responds to the two basic means of the user input - the keyboard and the mouse. Below described three aspects of the input handling - the event-driven, the polling and the simulated input issues. The event-driven input is the more or less natural way of communicating with the user, so when the user presses the key or moves the mouse, a system event occurs and triggers the notification in one or more widgets. Polling methods provide the immediate state of the input devices; the polling is rarely employed, primarily because of its limited usability, and because the information it provides is passed to the notification callbacks anyway. The simulated input is little more than "notify()" call with specifically crafted parameters. It interacts with the system, so the emulation can gain the higher level of similarity to the user actions. The simulated input functions allow the notifications to be called right away, or post it, delaying the notification until the next event loop invocation.

  Keyboard

Event-driven
    Keyboard input generates several notifications, where the most important are "KeyDown" and "KeyUp". Both have almost the same list of parameters ( see API ), that contain the key code, its modifiers ( if any ) that were pressed and an eventual character code. The algorithms that extract the meaning of the key, for example, discretion between character and functional keys etc are not described here. The reader is advised to look at Prima::KeySelector module, which provides convenience functions for keyboard input values transformations, and to the Prima::Edit and Prima::InputLine modules, the classes that use extensively the keyboard input. But in short, the key code is one of the "kb::XXX" ( like, kb::F10, kb::Esc ) constants, and the modifier value is a combination of the "km::XXX" ( km::Ctrl, km::Shift) constants. The notable exception is kb::None value, which hints that the character code is of value. Some other "kb::XXX"-marked keys have the character code as well, and it is up to a programmer how to treat these combinations. It is advised, however, to look at the key code first, and then to the character code.

    "KeyDown" event has also the repeat integer parameter, that shows the repetitive count how many times the key was pressed. Usually it is 1, but if a widget was not able to get its portion of events between the key presses, its value can be higher. If a code doesn't check for this parameter, some keyboard input may be lost. If the code will be too much complicated by introducing the repeat-value, one may consider setting the "::briefKeys" property to 0. "::briefKeys", the boolean property, is 1 by default. If set to 0, it guarantees that the repeat value will always be 1, but with the price of certain under-optimization. If the core "KeyDown" processing code sees repeat value greater than 1, it simply calls the notification again.

    Along with these two notifications, the "TranslateAccel" event is generated after "KeyDown", if the focused widget is not interested in the key event. Its usage covers the needs of the other widgets that are willing to read the user input, even being out of focus. A notable example can be a button with a hot key, that reacts on the key press when the focus is elsewhere within its top-level window. "TranslateAccel" has same parameters as "KeyDown", except the REPEAT parameter.

    Such out-of-focus input is also used with built-in menu keys translations. If a descendant of Prima::AbstractMenu is in the reach of the widget tree hierarchy, then it is checked whether it contains some hot keys that match the user input. See Prima::Menu for the details. In particular, Prima::Widget has "::accelTable" property, a mere slot for an object that contains a table of hot keys mappings to custom subroutines.

Polling
    The polling function for the keyboard is limited to the modifier keys only. "get_shift_state()" method returns the press state of the modifier keys, a combination of "km::XXX" constants.

Simulated input
    There are two methods, corresponding to the major notifications - "key_up()" and "key_down()", that accept the same parameters as the "KeyUp" and "KeyDown" notifications do, plus the POST boolean flag. See "API" for details.

    These methods are convenience wrappers for "key_event()" method, which is never used directly.

  Mouse

Event-driven
    Mouse notifications are send in response when the user moves the mouse, or presses and releases mouse buttons. The notifications are logically grouped in two sets, the first contains "MouseDown", "MouseUp", "MouseClick", and "MouseWheel", and the second - "MouseMove", "MouseEnter", end "MouseLeave".

    The first set deals with button actions. Pressing, de-pressing, clicking ( and double-clicking ), the turn of mouse wheel correspond to the four notifications. The notifications are sent together with the mouse pointer coordinates, the button that was touched, and the eventual modifier keys that were pressed. In addition, "MouseClick" provides the boolean flag if the click was single or double, and "MouseWheel" - the Z-range of the wheel turn. These notifications occur when the mouse event occurs within the geometrical bounds of a widget, with one notable exception, when a widget is in capture mode. If the "::capture" is set to 1, then these events are sent to the widget even if the mouse pointer is outside, and not sent to the widgets and windows that reside under the pointer.

    The second set deals with the pointer movements. When the pointer passes over a widget, it receives first "MouseEnter", then series of "MouseMove", and finally "MouseLeave". "MouseMove" and "MouseEnter" notifications provide X,Y-coordinates and modificator keys; "MouseLeave" passes no parameters.

Polling
    The mouse input polling procedures are "get_mouse_state()" method, that returns combination of "mb::XXX" constants, and the "::pointerPos" two-integer property that reports the current position of the mouse pointer.

Simulated input
    There are five methods, corresponding to the mouse events - "mouse_up()", "mouse_down()", "mouse_click()", "mouse_wheel()" and "mouse_move()", that accept the same parameters as their event counterparts do, plus the POST boolean flag. See "API" for details.

    These methods are convenience wrappers for "mouse_event()" method, which is never used directly.

Color schemes
Prima::Drawable deals only with such color values, that can be unambiguously decomposed to their red, green and blue components. Prima::Widget extends the range of the values acceptable by its color properties, introducing the color schemes. The color can be set indirectly, without prior knowledge of what is its RGB value. There are several constants defined in "cl::" name space, that correspond to the default values of different color properties of a widget.

Prima::Widget revises the usage of "::color" and "::backColor", the properties inherited from Prima::Drawable. Their values are widget's 'foreground' and 'background' colors, in addition to their function as template values. Moreover, their dynamic change induces the repainting of a widget, and they can be inherited from the owner. The inheritance is governed by properties "::ownerColor" and "::ownerBackColor". While these are true, changes to owner "::color" or "::backColor" copied automatically to a widget. Once the widget's "::color" or "::backColor" are explicitly set, the owner link breaks automatically by setting "::ownerColor" or "::ownerBackColor" to 0.

In addition to these two color properties, Prima::Widget introduces six others. These are "::disabledColor", "::disabledBackColor", "::hiliteColor", "::hiliteBackColor", "::light3DColor", and "::dark3DColor". The 'disabled' color pair contains the values that are expected to be used as foreground and background when a widget is in the disabled state ( see API, "::enabled" property ). The 'hilite' values serve as the colors for representation of selection inside a widget. Selection may be of any kind, and some widgets do not provide any. But for those that do, the 'hilite' color values provide distinct alternative colors. Examples are selections in the text widgets, or in the list boxes. The last pair, "::light3DColor" and "::dark3DColor" is used for drawing 3D-looking outlines of a widget. The purpose of all these properties is the adequate usage of the color settings, selected by the user using system-specific tools, so the program written with the toolkit would look not such different, and more or less conformant to the user's color preferences.

The additional "cl::" constants, mentioned above, represent these eight color properties. These named correspondingly, cl::NormalText, cl::Normal, cl::HiliteText, cl::Hilite, cl::DisabledText, cl::Disabled, cl::Light3DColor and cl::Dark3DColor. cl::NormalText is alias to cl::Fore, and cl::Normal - to cl::Back. Another constant set, "ci::" can be used with the "::colorIndex" property, a multiplexer for all eight color properties. "ci::" constants mimic their non-RGB "cl::" counterparts, so the call "hiliteBackColor(cl::Red)" is equal to "colorIndex(ci::Hilite, cl::Red)".

Mapping from these constants to the RGB color representation is used with "map_color()" method. These "cl::" constants alone are sufficient for acquiring the default values, but the toolkit provides wider functionality than this. The "cl::" constants can be combined with the "wc::" constants, that represent standard widget class. The widget class is implicitly used when single "cl::" constant is used; its value is read from the "::widgetClass" property, unless one of "wc::" constants is combined with the non-RGB "cl::" value. "wc::" constants are described in "API"; their usage can make call of, for example, "backColor( cl::Back)" on a button and on an input line result in different colors, because the "cl::Back" is translated in the first case into "cl::Back|wc::Button", and in another - "cl::Back|wc::InputLine".

Dynamic change of the color properties result in the "ColorChanged" notification.

Fonts
Prima::Widget does not change the handling of fonts - the font selection inside and outside "begin_paint()"/"end_paint()" is not different at all. A matter of difference is how does Prima::Widget select the default font.

First, if the "::ownerFont" property is set to 1, then font of the owner is copied to the widget, and is maintained all the time while the property is true. If it is not, the default font values read from the system.

The default font metrics for a widget returned by "get_default_font()" method, that often deals with system-dependent and user-selected preferences ( see "Additional resources" ). Because a widget can host an eventual Prima::Popup object, it contains "get_default_popup_font()" method, that returns the default font for the popup objects. The dynamic popup font settings governed, naturally, by the "::popupFont" property. Prima::Window extends the functionality to "get_default_menu_font()" and the "::menuFont" property.

Dynamic change of the font property results in the "FontChanged" notification.

Additional resources
The resources, operated via Prima::Widget class but not that strictly bound to the widget concept, are gathered in this section. The section includes overview of pointer, cursor, hint, menu objects and user-specified resources.

  Pointer
The mouse pointer is the shared resource, that can change its visual representation when it hovers over different kinds of widgets. It is usually a good practice for a text field, for example, set the pointer icon to a jagged vertical line, or indicate a moving window with a cross-arrowed pointer.

A widget can select either one of the predefined system pointers, mapped by the "cr::XXX" constant set, or supply its own pointer icon of an arbitrary size and color depth.

NB: Not all systems allow the colored pointer icons. System value under sv::ColorPointer index containing a boolean value, whether the colored icons are allowed or not.

In general, the "::pointer" property is enough for these actions. It discerns whether it has an icon or a constant passed, and sets the appropriate properties. These properties are also accessible separately, although their usage is not encouraged, primarily because of the tangled relationship between them. These properties are: "::pointerType", "::pointerIcon", and "::pointerHotSpot". See their details in the "API" sections.

Another property, which is present only in Prima::Application name space is called "::pointerVisible", and governs the visibility of the pointer - but for all widget instances at once.

  Cursor
The cursor is a blinking rectangular area, indicating the availability of the input focus in a widget. There can be only one active cursor per a GUI space, or none at all. Prima::Widget provides several cursor properties: "::cursorVisible", "::cursorPos", and "::cursorSize". There are also two methods, "show_cursor()" and "hide_cursor()", which are not the convenience shortcuts but the functions accounting the cursor hide count. If "hide_cursor()" was called three times, then "show_cursor()" must be called three times as well for the cursor to become visible.

  Hint
"::hint" is a text string, that usually describes the widget's purpose to the user in a brief manner. If the mouse pointer is hovered over the widget longer than some timeout ( see Prima::Application::hintPause ), then a label appears with the hint text, until the pointer is drawn away. The hint behavior is governed by Prima::Application, but a widget can do two additional things about hint: it can enable and disable it by calling "::showHint" property, and it can inherit the owner's "::hint" and "::showHint" properties using "::ownerHint" and "::ownerShowHint" properties. If, for example, "::ownerHint" is set to 1, then "::hint" value is automatically copied from the widget's owner, when it changes. If, however, the widget's "::hint" or "::showHint" are explicitly set, the owner link breaks automatically by setting "::ownerHint" or "::ownerShowHint" to 0.

The widget can also operate the "::hintVisible" property, that shows or hides the hint label immediately, if the mouse pointer is inside the widget's boundaries.

  Menu objects
The default functionality of Prima::Widget coexists with two kinds of the Prima::AbstractMenu descendants - Prima::AccelTable and Prima::Popup ( Prima::Window is also equipped with Prima::Menu reference). The "::items" property of these objects are accessible through "::accelItems" and "::popupItems", whereas the objects themselves - through "::accelTable" and "::popup", correspondingly. As mentioned in "User input", these objects hook the user keyboard input and call the programmer-defined callback subroutine if the key stroke equals to one of their table values. As for "::accelTable", its function ends here. "::popup" provides access to a context pop-up menu, which can be invoked by either right-clicking or pressing a system-dependent key combination. As a little customization, the "::popupColorIndex" and "::popupFont" properties are introduced. ( "::popupColorIndex" is multiplexed to "::popupColor", "::popupHiliteColor", "::popupHiliteBackColor", etc etc properties exactly like the "::colorIndex" property ).

The font and color of a menu object might not always be writable. The underlying system capabilities in this area range from total inability for a program to manage the menu fonts and colors in Win32, to a sport in interactive changing menu fonts and colors in OS/2.

The Prima::Window class provides equivalent methods for the menu bar, introducing "::menu", "::menuItems", "::menuColorIndex" ( with multiplexing ) and "::menuFont" properties.

  User-specified resources
It is considered a good idea to incorporate the user preferences into the toolkit look-and-feel. Prima::Widget relies to the system-specific code that tries to map these preferences as close as possible to the toolkit paradigm.

Unix version employs XRDB ( X resource database ), which is the natural way for the user to tell the preferences with fine granularity. Win32 and OS/2 read the setting that the user has to set interactively, using system tools. Nevertheless, the toolkit can not emulate all user settings that are available on the supported platforms; it rather takes a 'least common denominator', which is colors and fonts. "fetch_resource()" method is capable of returning any of such settings, provided it's format is font, color or a string. The method is rarely called directly.

The appealing idea of making every widget property adjustable via the user-specified resources is not implemented in full. It can be accomplished up to a certain degree using "fetch_resource()" existing functionality, but it is believed that calling up the method for the every property for the every widget created is prohibitively expensive.

API

  Properties

accelItems [ ITEM_LIST ]
    Manages items of a Prima::AccelTable object associated with a widget. The ITEM_LIST format is same as "Prima::AbstractMenu::items" and is described in Prima::Menu.

    See also: "accelTable"

accelTable OBJECT
    Manages a Prima::AccelTable object associated with a widget. The sole purpose of the accelTable object is to provide convenience mapping of key combinations to anonymous subroutines. Instead of writing an interface specifically for Prima::Widget, the existing interface of Prima::AbstractMenu was taken.

    The accelTable object can be destroyed safely; its cancellation can be done either via "accelTable(undef)" or "destroy()" call.

    Default value: undef

    See also: "accelItems"

autoEnableChildren BOOLEAN
    If TRUE, all immediate children widgets maintain the same "enabled" state as the widget. This property is useful for the group-like widgets ( ComboBox, SpinEdit etc ), that employ their children for visual representation.

    Default value: 0

backColor COLOR
    In widget paint state, reflects background color in the graphic context. In widget normal state, manages the basic background color. If changed, initiates "ColorChanged" notification and repaints the widget.

    See also: "color", "colorIndex", "ColorChanged"

bottom INTEGER
    Maintains the lower boundary of a widget. If changed, does not affect the widget height; but does so, if called in "set()" together with "::top".

    See also: "left", "right", "top", "origin", "rect", "growMode", "Move"

briefKeys BOOLEAN
    If 1, contracts the repetitive key press events into one notification, increasing REPEAT parameter of "KeyDown" callbacks. If 0, REPEAT parameter is always 1.

    Default value: 1

    See also: "KeyDown"

buffered BOOLEAN
    If 1, a widget "Paint" callback draws not on the screen, but on the off-screen memory instead. The memory content is copied to the screen then. Used when complex drawing methods are used, or if output smoothness is desired.

    This behavior can not be always granted, however. If there is not enough memory, then widget draws in the usual manner.

    Default value: 0

    See also: "Paint"

capture BOOLEAN, CLIP_OBJECT = undef
    Manipulates capturing of the mouse events. If 1, the mouse events are not passed to the widget the mouse pointer is over, but are redirected to the caller widget. The call for capture might not be always granted due the race conditions between programs.

    If CLIP_OBJECT widget is defined in set-mode call, the pointer movements are confined to CLIP_OBJECT inferior.

    See also: "MouseDown", "MouseUp", "MouseMove", "MouseWheel", "MouseClick".

centered BOOLEAN
    A write-only property. Once set, widget is centered by X and Y axis relative to its owner.

    See also: "x_centered", "y_centered", "growMode", "origin", "Move".

clipOwner BOOLEAN
    If 1, a widget is clipped by its owner boundaries. It is the default and expected behavior. If clipOwner is 0, a widget behaves differently: it does not clipped by the owner, it is not moved together with the parent, the origin offset is calculated not from the owner's coordinates but from the screen, and mouse events in a widget do not transgress to the top-level window decorations. In short, it itself becomes a top-level window, that, contrary to the one created from Prima::Window class, does not have any interference with system-dependent window stacking and positioning ( and any other ) policy, and is not ornamented by the window manager decorations.

    Default value: 1

    See "Parent-children relationship"

    See also: "Prima::Object" owner section, "parentHandle"

color COLOR
    In widget paint state, reflects foreground color in the graphic context. In widget normal state, manages the basic foreground color. If changed, initiates "ColorChanged" notification and repaints the widget.

    See also: "backColor", "colorIndex", "ColorChanged"

colorIndex INDEX, COLOR
    Manages the basic color properties indirectly, by accessing via "ci::XXX" constant. Is a complete alias for "::color", "::backColor", "::hiliteColor", "::hiliteBackColor", "::disabledColor", "::disabledBackColor", "::light3DColor", and "::dark3DColor" properties. The "ci::XXX" constants are:

       ci::NormalText or ci::Fore
       ci::Normal or ci::Back
       ci::HiliteText
       ci::Hilite
       ci::DisabledText
       ci::Disabled
       ci::Light3DColor
       ci::Dark3DColor

    The non-RGB "cl::" constants, specific to the Prima::Widget color usage are identical to their "ci::" counterparts:

       cl::NormalText or cl::Fore
       cl::Normal or cl::Back
       cl::HiliteText
       cl::Hilite
       cl::DisabledText
       cl::Disabled
       cl::Light3DColor
       cl::Dark3DColor

    See also: "color", "backColor", "ColorChanged"

current BOOLEAN
    If 1, a widget (or one of its children) is marked as the one to be focused ( or selected) when the owner widget receives "select()" call. Within children widgets, only one or none at all can be marked as a current.

    See also: "currentWidget", "selectable", "selected", "selectedWidget", "focused"

currentWidget OBJECT
    Points to a children widget, that is to be focused ( or selected) when the owner widget receives "select()" call.

    See also: "current", "selectable", "selected", "selectedWidget", "focused"

cursorPos X_OFFSET Y_OFFSET
    Specifies the lower left corner of the cursor

    See also: "cursorSize", "cursorVisible"

cursorSize WIDTH HEIGHT
    Specifies width and height of the cursor

    See also: "cursorPos", "cursorVisible"

cursorVisible BOOLEAN
    Specifies cursor visibility flag. Default value is 0.

    See also: "cursorSize", "cursorPos"

dark3DColor COLOR
    The color used to draw dark shades.

    See also: "light3DColor", "colorIndex", "ColorChanged"

designScale X_SCALE Y_SCALE
    The width and height of a font, that was used when a widget ( usually a dialog or a grouping widget ) was designed.

    See also: "scaleChildren", "width", "height", "size", "font"

disabledBackColor COLOR
    The color used to substitute "::backColor" when a widget is in its disabled state.

    See also: "disabledColor", "colorIndex", "ColorChanged"

disabledColor COLOR
    The color used to substitute "::color" when a widget is in its disabled state.

    See also: "disabledBackColor", "colorIndex", "ColorChanged"

enabled BOOLEAN
    Specifies if a widget can accept focus, keyboard and mouse events. Default value is 1, however, being 'enabled' does not automatically allow the widget become focused. Only the reverse is true - if enabled is 0, focusing can never happen.

    See also: "responsive", "visible", "Enable", "Disable"

font %FONT
    Manages font context. Same syntax as in Prima::Drawable. If changed, initiates "FontChanged" notification and repaints the widget.

    See also: "designScale", "FontChanged", "ColorChanged"

geometry INTEGER
    Selects one of the available geometry managers. The corresponding integer constants are:

       gt::GrowMode, gt::Default - the default grow-mode algorithm
       gt::Pack                  - Tk packer
       gt::Place                 - Tk placer

    See "growMode", Prima::Widget::pack, Prima::Widget::place.

growMode MODE
    Specifies widget behavior, when its owner is resized or moved. MODE can be 0 ( default ) or a combination of the following constants:

    Basic constants
         gm::GrowLoX      widget's left side is kept in constant
                          distance from owner's right side
         gm::GrowLoY      widget's bottom side is kept in constant
                          distance from owner's top side
         gm::GrowHiX      widget's right side is kept in constant
                          distance from owner's right side
         gm::GrowHiY      widget's top side is kept in constant
                          distance from owner's top side
         gm::XCenter      widget is kept in center on its owner's
                          horizontal axis
         gm::YCenter      widget is kept in center on its owner's
                          vertical axis
         gm::DontCare     widgets origin is maintained constant relative
                          to the screen

    Derived or aliased constants
         gm::GrowAll      gm::GrowLoX|gm::GrowLoY|gm::GrowHiX|gm::GrowHiY
         gm::Center       gm::XCenter|gm::YCenter
         gm::Client       gm::GrowHiX|gm::GrowHiY
         gm::Right        gm::GrowLoX|gm::GrowHiY
         gm::Left         gm::GrowHiY
         gm::Floor        gm::GrowHiX

    See also: "Move", "origin"

firstClick BOOLEAN
    If 0, a widget bypasses first mouse click on it, if the top-level window it belongs to was not activated, so selecting such a widget it takes two mouse clicks.

    Default value is 1

    See also: "MouseDown", "selectable", "selected", "focused", "selectingButtons"

focused BOOLEAN
    Specifies whether a widget possesses the input focus or not. Disregards "::selectable" property on set-call.

    See also: "selectable", "selected", "selectedWidget", "KeyDown"

geomWidth, geomHeight, geomSize
    Three properties that select geometry request size. Writing and reading to "::geomWidth" and "::geomHeight" is equivalent to "::geomSize". The properies are run-time only, and behave differently under different circumstances:

    *   As the properties are run-time only, they can not be set in the profile, and their initial value is fetched from "::size" property. Thus, setting the explicit size is aditionally sets the advised size in case the widget is to be used with the Tk geometry managers.

    *   Setting the properties under the "gt::GrowMode" geometry manager also sets the corresponding "::width", "::height", or "::size". When the properties are read, though, the real size properties are not read; the values are kept separately.

    *   Setting the properties under Tk geometry managers cause widgets size and position changed according to the geometry manager policy.

height
    Maintains the height of a widget.

    See also: "width", "growMode", "Move", "Size", "get_virtual_size", "sizeMax", "sizeMin"

helpContext STRING
    A string that binds a widget, a logical part it plays with the application and an interactive help topic. STRING format is defined as POD link ( see perlpod ) - "manpage/section", where 'manpage' is the file with POD content and 'section' is the topic inside the manpage.

    See also: "help"

hiliteBackColor COLOR
    The color used to draw alternate background areas with high contrast.

    See also: "hiliteColor", "colorIndex", "ColorChanged"

hiliteColor COLOR
    The color used to draw alternate foreground areas with high contrast.

    See also: "hiliteBackColor", "colorIndex", "ColorChanged"

hint TEXT
    A text, shown under mouse pointer if it is hovered over a widget longer than "Prima::Application::hintPause" timeout. The text shows only if the "::showHint" is 1.

    See also: "hintVisible", "showHint", "ownerHint", "ownerShowHint"

hintVisible BOOLEAN
    If called in get-form, returns whether the hint label is shown or not. If in set-form, immediately turns on or off the hint label, disregarding the timeouts. It does regard the mouse pointer location, however, and does not turn on the hint label if the pointer is away.

    See also: "hint", "showHint", "ownerHint", "ownerShowHint"

left INTEGER
    Maintains the left boundary of a widget. If changed, does not affect the widget width; but does so, if called in "set()" together with "::right".

    See also: "bottom", "right", "top", "origin", "rect", "growMode", "Move"

light3DColor COLOR
    The color used to draw light shades.

    See also: "dark3DColor", "colorIndex", "ColorChanged"

ownerBackColor BOOLEAN
    If 1, the background color is synchronized with the owner's. Automatically set to 0 if "::backColor" property is explicitly set.

    See also: "ownerColor", "backColor", "colorIndex"

ownerColor BOOLEAN
    If 1, the foreground color is synchronized with the owner's. Automatically set to 0 if "::color" property is explicitly set.

    See also: "ownerBackColor", "color", "colorIndex"

ownerFont BOOLEAN
    If 1, the font is synchronized with the owner's. Automatically set to 0 if "::font" property is explicitly set.

    See also: "font", "FontChanged"

ownerHint BOOLEAN
    If 1, the hint is synchronized with the owner's. Automatically set to 0 if "::hint" property is explicitly set.

    See also: "hint", "showHint", "hintVisible", "ownerShowHint"

ownerShowHint BOOLEAN
    If 1, the show hint flag is synchronized with the owner's. Automatically set to 0 if "::showHint" property is explicitly set.

    See also: "hint", "showHint", "hintVisible", "ownerHint"

ownerPalette BOOLEAN
    If 1, the palette array is synchronized with the owner's. Automatically set to 0 if "::palette" property is explicitly set.

    See also: "palette"

origin X Y
    Maintains the left and bottom boundaries of a widget relative to its owner ( or to the screen if "::clipOwner" is set to 0 ).

    See also: "bottom", "right", "top", "left", "rect", "growMode", "Move"

packInfo %OPTIONS
    See Prima::Widget::pack

palette [ @PALETTE ]
    Specifies array of colors, that are desired to be present into the system palette, as close to the PALETTE as possible. This property works only if the graphic device allows palette operations. See "palette" in Prima::Drawable.

    See also: "ownerPalette"

parentHandle SYSTEM_WINDOW
    If SYSTEM_WINDOW is a valid system-dependent window handle, then a widget becomes the child of the window specified, given the widget's "::clipOwner" is 0. The parent window can belong to another application.

    Default value is undef.

    See also: "clipOwner"

placeInfo %OPTIONS
    See Prima::Widget::place

pointer cr::XXX or ICON
    Specifies the pointer icon; discerns between "cr::XXX" constants and an icon. If an icon contains a hash variable "__pointerHotSpot" with an array of two integers, these integers will be treated as the pointer hot spot. In get-mode call, this variable is automatically assigned to an icon, if the result is an icon object.

    See also: "pointerHotSpot", "pointerIcon", "pointerType"

pointerHotSpot X_OFFSET Y_OFFSET
    Specifies the hot spot coordinates of a pointer icon, associated with a widget.

    See also: "pointer", "pointerIcon", "pointerType"

pointerIcon ICON
    Specifies the pointer icon, associated with a widget.

    See also: "pointerHotSpot", "pointer", "pointerType"

pointerPos X_OFFSET Y_OFFSET
    Specifies the mouse pointer coordinates relative to widget's coordinates.

    See also: "get_mouse_state", "screen_to_client", "client_to_screen"

pointerType TYPE
    Specifies the type of the pointer, associated with the widget. TYPE can accept one constant of "cr::XXX" set:

       cr::Default                 same pointer type as owner's
       cr::Arrow                   arrow pointer
       cr::Text                    text entry cursor-like pointer
       cr::Wait                    hourglass
       cr::Size                    general size action pointer
       cr::Move                    general move action pointer
       cr::SizeWest, cr::SizeW     right-move action pointer
       cr::SizeEast, cr::SizeE     left-move action pointer
       cr::SizeWE                  general horizontal-move action pointer
       cr::SizeNorth, cr::SizeN    up-move action pointer
       cr::SizeSouth, cr::SizeS    down-move action pointer
       cr::SizeNS                  general vertical-move action pointer
       cr::SizeNW                  up-right move action pointer
       cr::SizeSE                  down-left move action pointer
       cr::SizeNE                  up-left move action pointer
       cr::SizeSW                  down-right move action pointer
       cr::Invalid                 invalid action pointer
       cr::User                    user-defined icon

    All constants except "cr::User" and "cr::Default" present a system-defined pointers, their icons and hot spot offsets. "cr::User" is a sign that an icon object was specified explicitly via "::pointerIcon" property. "cr::Default" is a way to tell that a widget inherits its owner pointer type, no matter is it a system-defined pointer or a custom icon.

    See also: "pointerHotSpot", "pointerIcon", "pointer"

popup OBJECT
    Manages a Prima::Popup object associated with a widget. The purpose of the popup object is to show a context menu when the user right-clicks or selects the corresponding keyboard combination. Prima::Widget can host many children objects, Prima::Popup as well. But only the one that is set in "::popup" property will be activated automatically.

    The popup object can be destroyed safely; its cancellation can be done either via "popup(undef)" or "destroy()" call.

    See also: "Prima::Menu", "Popup", "Menu", "popupItems", "popupColorIndex", "popupFont"

popupColorIndex INDEX, COLOR
    Maintains eight color properties of a pop-up context menu, associated with a widget. INDEX must be one of "ci::XXX" constants ( see "::colorIndex" property ).

    See also: "popupItems", "popupFont", "popup"

popupColor COLOR
    Basic foreground in a popup context menu color.

    See also: "popupItems", "popupColorIndex", "popupFont", "popup"

popupBackColor COLOR
    Basic background in a popup context menu color.

    See also: "popupItems", "popupColorIndex", "popupFont", "popup"

popupDark3DColor COLOR
    Color for drawing dark shadings in a popup context menu.

    See also: "popupItems", "popupColorIndex", "popupFont", "popup"

popupDisabledColor COLOR
    Foreground color for disabled items in a popup context menu.

    See also: "popupItems", "popupColorIndex", "popupFont", "popup"

popupDisabledBackColor COLOR
    Background color for disabled items in a popup context menu.

    See also: "popupItems", "popupColorIndex", "popupFont", "popup"

popupFont %FONT
    Maintains the font of a pop-up context menu, associated with a widget.

    See also: "popupItems", "popupColorIndex", "popup"

popupHiliteColor COLOR
    Foreground color for selected items in a popup context menu.

    See also: "popupItems", "popupColorIndex", "popupFont", "popup"

popupHiliteBackColor COLOR
    Background color for selected items in a popup context menu.

    See also: "popupItems", "popupColorIndex", "popupFont", "popup"

popupItems [ ITEM_LIST ]
    Manages items of a Prima::Popup object associated with a widget. The ITEM_LIST format is same as "Prima::AbstractMenu::items" and is described in Prima::Menu.

    See also: "popup", "popupColorIndex", "popupFont"

popupLight3DColor COLOR
    Color for drawing light shadings in a popup context menu.

    See also: "popupItems", "popupColorIndex", "popupFont", "popup"

rect X_LEFT_OFFSET Y_BOTTOM_OFFSET X_RIGHT_OFFSET Y_TOP_OFFSET
    Maintains the rectangular boundaries of a widget relative to its owner ( or to the screen if "::clipOwner" is set to 0 ).

    See also: "bottom", "right", "top", "left", "origin", "width", "height", "size" "growMode", "Move", "Size", "get_virtual_size", "sizeMax", "sizeMin"

right INTEGER
    Maintains the right boundary of a widget. If changed, does not affect the widget width; but does so, if called in "set()" together with "::left".

    See also: "left", "bottom", "top", "origin", "rect", "growMode", "Move"

scaleChildren BOOLEAN
    If a widget has "::scaleChildren" set to 1, then the newly-created children widgets inserted in it will be scaled corresponding to the owner's "::designScale", given that widget's "::designScale" is not "undef" and the owner's is not [0,0].

    Default is 1.

    See also: "designScale"

selectable BOOLEAN
    If 1, a widget can be granted focus implicitly, or by means of the user actions. "select()" regards this property, and does not focus a widget that has "::selectable" set to 0.

    Default value is 0

    See also: "current", "currentWidget", "selected", "selectedWidget", "focused"

selected BOOLEAN
    If called in get-mode, returns whether a widget or one of its (grand-) children is focused. If in set-mode, either simply turns the system with no-focus state ( if 0 ), or sends input focus to itself or one of the widgets tracked down by "::currentWidget" chain.

    See also: "current", "currentWidget", "selectable", "selectedWidget", "focused"

selectedWidget OBJECT
    Points to a child widget, that has property "::selected" set to 1.

    See also: "current", "currentWidget", "selectable", "selected", "focused"

selectingButtons FLAGS
    FLAGS is a combination of "mb::XXX" ( mouse button ) flags. If a widget receives a click with a mouse button, that has the corresponding bit set in "::selectingButtons", then "select()" is called.

    See also: "MouseDown", "firstClick", "selectable", "selected", "focused"

shape IMAGE
    Maintains the non-rectangular shape of a widget. IMAGE is monochrome Prima::Image, with 0 bits treated as transparent pixels, and 1 bits as opaque pixels.

    Successive only if "sv::ShapeExtension" value is true.

showHint BOOLEAN
    If 1, the toolkit is allowed to show the hint label over a widget. If 0, the display of the hint is forbidden. The "::hint" property must contain non-empty string as well, if the hint label must be shown.

    Default value is 1.

    See also: "hint", "ownerShowHint", "hintVisible", "ownerHint"

size WIDTH HEIGHT
    Maintains the width and height of a widget.

    See also: "width", "height" "growMode", "Move", "Size", "get_virtual_size", "sizeMax", "sizeMin"

sizeMax WIDTH HEIGHT
    Specifies the maximal size for a widget that it is allowed to accept.

    See also: "width", "height", "size" "growMode", "Move", "Size", "get_virtual_size", "sizeMin"

sizeMin WIDTH HEIGHT
    Specifies the minimal size for a widget that it is allowed to accept.

    See also: "width", "height", "size" "growMode", "Move", "Size", "get_virtual_size", "sizeMax"

syncPaint BOOLEAN
    If 0, the "Paint" request notifications are stacked until the event loop is called. If 1, every time the widget surface gets invalidated, the "Paint" notification is called.

    Default value is 0.

    See also: "invalidate_rect", "repaint", "validate_rect", "Paint"

tabOrder INTEGER
    Maintains the order in which tab- and shift-tab- key navigation algorithms select the sibling widgets. INTEGER is unique among the sibling widgets. In set mode, if INTEGER value is already taken, the occupier is assigned another unique value, but without destruction of a queue - widgets with ::tabOrder greater than of the widget, receive their new values too. Special value -1 is accepted as 'the end of list' indicator; the negative value is never returned.

    See also: "tabStop", "next_tab", "selectable", "selected", "focused"

tabStop BOOLEAN
    Specifies whether a widget is interested in tab- and shift-tab- key navigation or not.

    Default value is 1.

    See also: "tabOrder", "next_tab", "selectable", "selected", "focused"

text TEXT
    A text string for generic purpose. Many Prima::Widget descendants use this property heavily - buttons, labels, input lines etc, but Prima::Widget itself does not.

top INTEGER
    Maintains the upper boundary of a widget. If changed, does not affect the widget height; but does so, if called in "set()" together with "::bottom".

    See also: "left", "right", "bottom", "origin", "rect", "growMode", "Move"

transparent BOOLEAN
    Specifies whether the background of a widget before it starts painting is of any importance. If 1, a widget can gain certain transparency look if it does not clear the background during "Paint" event.

    Default value is 0

    See also: "Paint", "buffered".

visible BOOLEAN
    Specifies whether a widget is visible or not. See "Visibility".

    See also: "Show", "Hide", "showing", "exposed"

widgetClass CLASS
    Maintains the integer value, designating the color class that is defined by the system and is associated with Prima::Widget eight basic color properties. CLASS can be one of "wc::XXX" constants:

       wc::Undef
       wc::Button
       wc::CheckBox
       wc::Combo
       wc::Dialog
       wc::Edit
       wc::InputLine
       wc::Label
       wc::ListBox
       wc::Menu
       wc::Popup
       wc::Radio
       wc::ScrollBar
       wc::Slider
       wc::Widget or wc::Custom
       wc::Window
       wc::Application

    These constants are not associated with the toolkit classes; any class can use any of these constants in "::widgetClass".

    See also: "map_color", "colorIndex"

width WIDTH
    Maintains the width of a widget.

    See also: "height" "growMode", "Move", "Size", "get_virtual_size", "sizeMax", "sizeMin"

x_centered BOOLEAN
    A write-only property. Once set, widget is centered by the horizontal axis relative to its owner.

    See also: "centered", "y_centered", "growMode", "origin", "Move".

y_centered BOOLEAN
    A write-only property. Once set, widget is centered by the vertical axis relative to its owner.

    See also: "x_centered", "centered", "growMode", "origin", "Move".

  Methods

bring_to_front
    Sends a widget on top of all other siblings widgets

    See also: "insert_behind", "send_to_back", "ZOrderChanged" ,"first", "next", "prev", "last"

can_close
    Sends "Close" message, and returns its boolean exit state.

    See also: "Close", "close"

client_to_screen @OFFSETS
    Maps array of X and Y integer offsets from widget to screen coordinates. Returns the mapped OFFSETS.

    See also: "screen_to_client", "clipOwner"

close
    Calls "can_close()", and if successful, destroys a widget. Returns the "can_close()" result.

    See also: "can_close", "Close"

defocus
    Alias for focused(0) call

    See also: "focus", "focused", "Enter", "Leave"

deselect
    Alias for selected(0) call

    See also: "select", "selected", "Enter", "Leave"

exposed
    Returns a boolean value, indicating whether a widget is at least partly visible on the screen. Never returns 1 if a widget has "::visible" set to 0.

    See also: "visible", "showing", "Show", "Hide"

fetch_resource CLASS_NAME, NAME, CLASS_RESOURCE, RESOURCE, OWNER, RESOURCE_TYPE = fr::String
    Returns a system-defined scalar of resource, defined by the widget hierarchy, its class, name and owner. RESOURCE_TYPE can be one of type qualificators:

       fr::Color  - color resource
       fr::Font   - font resource
       fs::String - text string resource

    Such a number of the parameters is used because the method can be called before a widget is created. CLASS_NAME is widget class string, NAME is widget name. CLASS_RESOURCE is class of resource, and RESOURCE is the resource name.

    For example, resources 'color' and 'disabledColor' belong to the resource class 'Foreground'.

first
    Returns the first ( from bottom ) sibling widget in Z-order.

    See also: "last", "next", "prev"

focus
    Alias for focused(1) call

    See also: "defocus", "focused", "Enter", "Leave"

hide
    Sets widget "::visible" to 0.

    See also: "hide", "visible", "Show", "Hide", "showing", "exposed"

hide_cursor
    Hides the cursor. As many times "hide_cursor()" was called, as many time its counterpart "show_cursor()" must be called to reach the cursor's initial state.

    See also: "show_cursor", "cursorVisible"

help
    Starts an interactive help viewer opened on "::helpContext" string value.

    The string value is combined from the widget's owner "::helpContext" strings if the latter is empty or begins with a slash. A special meaning is assigned to an empty string " " - the help() call fails when such value is found to be the section component. This feature can be useful when a window or a dialog presents a standalone functionality in a separate module, and the documentation is related more to the module than to an embedding program. In such case, the grouping widget holds "::helpContext" as a pod manpage name with a trailing slash, and its children widgets are assigned "::helpContext" to the topics without the manpage but the leading slash instead. If the grouping widget has an empty string " " as "::helpContext" then the help is forced to be unavailable for all the children widgets.

    See also: "helpContext"

insert CLASS, %PROFILE [[ CLASS, %PROFILE], ... ]
    Creates one or more widgets with "owner" property set to the caller widget, and returns the list of references to the newly created widgets.

    Has two calling formats:

    Single widget
          $parent-> insert( 'Child::Class',
             name => 'child',
             ....
          );

    Multiple widgets
          $parent-> insert(
            [
               'Child::Class1',
                  name => 'child1',
                  ....
            ],
            [
               'Child::Class2',
                  name => 'child2',
                  ....
            ],
          );

insert_behind OBJECT
    Sends a widget behind the OBJECT on Z-axis, given that the OBJECT is a sibling to the widget.

    See also: "bring_to_front", "send_to_back", "ZOrderChanged" ,"first", "next", "prev", "last"

invalidate_rect X_LEFT_OFFSET Y_BOTTOM_OFFSET X_RIGHT_OFFSET Y_TOP_OFFSET
    Marks the rectangular area of a widget as 'invalid', so re-painting of the area happens. See "Graphic content".

    See also: "validate_rect", "get_invalid_rect", "repaint", "Paint", "syncPaint", "update_view"

key_down CODE, KEY = kb::NoKey, MOD = 0, REPEAT = 1, POST = 0
    The method sends or posts ( POST flag ) simulated "KeyDown" event to the system. CODE, KEY, MOD and REPEAT are the parameters to be passed to the notification callbacks.

    See also: "key_up", "key_event", "KeyDown"

key_event COMMAND, CODE, KEY = kb::NoKey, MOD = 0, REPEAT = 1, POST = 0
    The method sends or posts ( POST flag ) simulated keyboard event to the system. CODE, KEY, MOD and REPEAT are the parameters to be passed to an eventual "KeyDown" or "KeyUp" notifications. COMMAND is allowed to be either "cm::KeyDown" or "cm::KeyUp".

    See also: "key_down", "key_up", "KeyDown", "KeyUp"

key_up CODE, KEY = kb::NoKey, MOD = 0, POST = 0
    The method sends or posts ( POST flag ) simulated "KeyUp" event to the system. CODE, KEY and MOD are the parameters to be passed to the notification callbacks.

    See also: "key_down", "key_event", "KeyUp"

last
    Returns the last ( the topmost ) sibling widget in Z-order.

    See also: "first", "next", "prev"

lock
    Turns off the ability of a widget to re-paint itself. As many times "lock()" was called, as may times its counterpart, "unlock()" must be called to enable re-painting again. Returns a boolean success flag.

    See also: "unlock", "repaint", "Paint", "get_locked"

map_color COLOR
    Transforms "cl::XXX" and "ci::XXX" combinations into RGB color representation and returns the result. If COLOR is already in RGB format, no changes are made.

    See also: "colorIndex"

mouse_click BUTTON = mb::Left, MOD = 0, X = 0, Y = 0, DBL_CLICK = 0, POST = 0
    The method sends or posts ( POST flag ) simulated "MouseClick" event to the system. BUTTON, MOD, X, Y, and DBL_CLICK are the parameters to be passed to the notification callbacks.

    See also: "MouseDown", "MouseUp", "MouseWheel", "MouseMove", "MouseEnter", "MouseLeave"

mouse_down BUTTON = mb::Left, MOD = 0, X = 0, Y = 0, POST = 0
    The method sends or posts ( POST flag ) simulated "MouseDown" event to the system. BUTTON, MOD, X, and Y are the parameters to be passed to the notification callbacks.

    See also: "MouseUp", "MouseWheel", "MouseClick", "MouseMove", "MouseEnter", "MouseLeave"

mouse_enter MOD = 0, X = 0, Y = 0, POST = 0
    The method sends or posts ( POST flag ) simulated "MouseEnter" event to the system. MOD, X, and Y are the parameters to be passed to the notification callbacks.

    See also: "MouseDown", "MouseUp", "MouseWheel", "MouseClick", "MouseMove", "MouseLeave"

mouse_event COMMAND = cm::MouseDown, BUTTON = mb::Left, MOD = 0, X = 0, Y = 0, DBL_CLICK = 0, POST = 0
    The method sends or posts ( POST flag ) simulated mouse event to the system. BUTTON, MOD, X, Y and DBL_CLICK are the parameters to be passed to an eventual mouse notifications. COMMAND is allowed to be one of "cm::MouseDown", "cm::MouseUp", "cm::MouseWheel", "cm::MouseClick", "cm::MouseMove", "cm::MouseEnter", "cm::MouseLeave" constants.

    See also: "mouse_down", "mouse_up", "mouse_wheel", "mouse_click", "mouse_move", "mouse_enter", "mouse_leave", "MouseDown", "MouseUp", "MouseWheel", "MouseClick", "MouseMove", "MouseEnter", "MouseLeave"

mouse_leave
    The method sends or posts ( POST flag ) simulated "MouseLeave" event to the system.

    See also: "MouseDown", "MouseUp", "MouseWheel", "MouseClick", "MouseMove", "MouseEnter", "MouseLeave"

mouse_move MOD = 0, X = 0, Y = 0, POST = 0
    The method sends or posts ( POST flag ) simulated "MouseMove" event to the system. MOD, X, and Y are the parameters to be passed to the notification callbacks.

    See also: "MouseDown", "MouseUp", "MouseWheel", "MouseClick", "MouseEnter", "MouseLeave"

mouse_up BUTTON = mb::Left, MOD = 0, X = 0, Y = 0, POST = 0
    The method sends or posts ( POST flag ) simulated "MouseUp" event to the system. BUTTON, MOD, X, and Y are the parameters to be passed to the notification callbacks.

    See also: "MouseDown", "MouseWheel", "MouseClick", "MouseMove", "MouseEnter", "MouseLeave"

mouse_wheel MOD = 0, X = 0, Y = 0, Z = 0, POST = 0
    The method sends or posts ( POST flag ) simulated "MouseUp" event to the system. MOD, X, Y and Z are the parameters to be passed to the notification callbacks.

    See also: "MouseDown", "MouseUp", "MouseClick", "MouseMove", "MouseEnter", "MouseLeave"

next
    Returns the neighbor sibling widget, next ( above ) in Z-order. If none found, undef is returned.

    See also: "first", "last", "prev"

next_tab FORWARD = 1
    Returns the next widget in the sorted by "::tabOrder" list of sibling widgets. FORWARD is a boolean lookup direction flag. If none found, the first ( or the last, depending on FORWARD flag ) widget is returned. Only widgets with "::tabStop" set to 1 participate.

    Also used by the internal keyboard navigation code.

    See also: "next_positional", "tabOrder", "tabStop", "selectable"

next_positional DELTA_X DELTA_Y
    Returns a sibling, (grand-)child of a sibling or (grand-)child widget, that matched best the direction specified by DELTA_X and DELTA_Y. At one time, only one of these parameters can be zero; another parameter must be either 1 or -1.

    Also used by the internal keyboard navigation code.

    See also: "next_tab", "origin"

pack, packForget, packSlaves
    See Prima::Widget::pack

place, placeForget, placeSlaves
    See Prima::Widget::place

prev
    Returns the neighbor sibling widget, previous ( below ) in Z-order. If none found, undef is returned.

    See also: "first", "last", "next"

repaint
    Marks the whole widget area as 'invalid', so re-painting of the area happens. See "Graphic content".

    See also: "validate_rect", "get_invalid_rect", "invalidate_rect", "Paint", "update_view", "syncPaint"

responsive
    Returns a boolean flag, indicating whether a widget and its owners have all "::enabled" 1 or not. Useful for fast check if a widget should respond to the user actions.

    See also: "enabled"

screen_to_client @OFFSETS
    Maps array of X and Y integer offsets from screen to widget coordinates. Returns the mapped OFFSETS.

    See also: "client_to_screen"

scroll DELTA_X DELTA_Y %OPTIONS
    Scrolls the graphic context area by DELTA_X and DELTA_Y pixels. OPTIONS is hash, that contains optional parameters to the scrolling procedure:

    clipRect [X1, Y1, X2, Y2]
        The clipping area is confined by X1, Y1, X2, Y2 rectangular area. If not specified, the clipping area covers the whole widget. Only the bits, covered by clipRect are affected. Bits scrolled from the outside of the rectangle to the inside are painted; bits scrolled from the inside of the rectangle to the outside are not painted.

    confineRect [X1, Y1, X2, Y2]
        The scrolling area is confined by X1, Y1, X2, Y2 rectangular area. If not specified, the scrolling area covers the whole widget.

    withChildren BOOLEAN
        If 1, the scrolling performs with the eventual children widgets change their positions to DELTA_X and DELTA_Y as well.

    Cannot be used inside paint state.

    See also: "Paint", "get_invalid_rect"

select
    Alias for selected(1) call

    See also: "deselect", "selected", "Enter", "Leave"

send_to_back
    Sends a widget at bottom of all other siblings widgets

    See also: "insert_behind", "bring_to_front", "ZOrderChanged" ,"first", "next", "prev", "last"

show
    Sets widget "::visible" to 1.

    See also: "hide", "visible", "Show", "Hide", "showing", "exposed"

show_cursor
    Shows the cursor. As many times "hide_cursor()" was called, as many time its counterpart "show_cursor()" must be called to reach the cursor's initial state.

    See also: "hide_cursor", "cursorVisible"

showing
    Returns a boolean value, indicating whether the widget and its owners have all "::visible" 1 or not.

unlock
    Turns on the ability of a widget to re-paint itself. As many times "lock()" was called, as may times its counterpart, "unlock()" must be called to enable re-painting again. When last "unlock()" is called, an implicit "repaint()" call is made. Returns a boolean success flag.

    See also: "lock", "repaint", "Paint", "get_locked"

update_view
    If any parts of a widget were marked as 'invalid' by either "invalidate_rect()" or "repaint()" calls or the exposure caused by window movements ( or any other), then "Paint" notification is immediately called. If no parts are invalid, no action is performed. If a widget has "::syncPaint" set to 1, "update_view()" is always a no-operation call.

    See also: "invalidate_rect", "get_invalid_rect", "repaint", "Paint", "syncPaint", "update_view"

validate_rect X_LEFT_OFFSET Y_BOTTOM_OFFSET X_RIGHT_OFFSET Y_TOP_OFFSET
    Reverses the effect of "invalidate_rect()", restoring the original, 'valid' state of widget area covered by the rectangular area passed. If a widget with previously invalid areas was wholly validated by this method, no "Paint" notifications occur.

    See also: "invalidate_rect", "get_invalid_rect", "repaint", "Paint", "syncPaint", "update_view"

  Get-methods

get_default_font
    Returns the default font for a Prima::Widget class.

    See also: "font"

get_default_popup_font
    Returns the default font for a Prima::Popup class.

    See also: "font"

get_invalid_rect
    Returns the result of successive calls "invalidate_rect()", "validate_rect()" and "repaint()", as a rectangular area ( four integers ) that cover all invalid regions in a widget. If none found, (0,0,0,0) is returned.

    See also: "validate_rect", "invalidate_rect", "repaint", "Paint", "syncPaint", "update_view"

get_handle
    Returns a system handle for a widget

    See also: "get_parent_handle"

get_locked
    Returns 1 if a widget is in "lock()" - initiated repaint-blocked state.

    See also: "lock", "unlock"

get_mouse_state
    Returns a combination of "mb::XXX" constants, reflecting the currently pressed mouse buttons.

    See also: "pointerPos", "get_shift_state"

get_parent
    Returns the owner widget that clips the widget boundaries, or application object if a widget is top-level.

    See also: "clipOwner"

get_parent_handle
    Returns a system handle for a parent of a widget, a window that belongs to another program. Returns 0 if the widget's owner and parent are in the same application and process space.

    See also: "get_handle", "clipOwner"

get_pointer_size
    Returns two integers, width and height of a icon, that the system accepts as valid for a pointer. If the icon is supplied that is more or less than these values, it is truncated or padded with transparency bits, but is not stretched. Can be called with class syntax.

get_shift_state
    Returns a combination of "km::XXX" constants, reflecting the currently pressed keyboard modificator buttons.

    See also: "get_shift_state"

get_virtual_size
    Returns virtual width and height of a widget. See "Geometry", Implicit size regulations.

    See also: "width", "height", "size" "growMode", "Move", "Size", "sizeMax", "sizeMin"

get_widgets or widgets
    Returns list of children widgets.

  Events

Change
    Generic notification, used for Prima::Widget descendants; Prima::Widget itself neither calls not uses the event. Designed to be called when an arbitrary major state of a widget is changed.

Click
    Generic notification, used for Prima::Widget descendants; Prima::Widget itself neither calls not uses the event. Designed to be called when an arbitrary major action for a widget is called.

Close
    Triggered by "can_close()" and "close()" functions. If the event flag is cleared during execution, these functions fail.

    See also: "close", "can_close"

ColorChanged INDEX
    Called when one of widget's color properties is changed, either by direct property change or by the system. INDEX is one of "ci::XXX" constants.

    See also: "colorIndex"

Disable
    Triggered by a successive enabled(0) call

    See also: "Enable", "enabled", "responsive"

DragDrop X Y
    Design in progress. Supposed to be triggered when a drag-and-drop session started by the widget. X and Y are mouse pointer coordinates on the session start.

    See also: "DragOver", "EndDrag"

DragOver X Y STATE
    Design in progress. Supposed to be called when a mouse pointer is passed over a widget during a drag-and-drop session. X and Y are mouse pointer coordinates, identical to "MouseMove" X Y parameters. STATE value is undefined.

    See also: "DragDrop", "EndDrag"

Enable
    Triggered by a successive enabled(1) call

    See also: "Disable", "enabled", "responsive"

EndDrag X Y
    Design in progress. Supposed to be called when a drag-and-drop session is finished successfully over a widget. X and Y are mouse pointer coordinates on the session end.

    See also: "DragDrop", "DragOver"

Enter
    Called when a widget receives the input focus.

    See also: "Leave", "focused", "selected"

FontChanged
    Called when a widget font is changed either by direct property change or by the system.

    See also: "font", "ColorChanged"

Hide
    Triggered by a successive visible(0) call

    See also: "Show", "visible", "showing", "exposed"

Hint SHOW_FLAG
    Called when the hint label is about to show or hide, depending on SHOW_FLAG. The hint show or hide action fails, if the event flag is cleared during execution.

    See also: "showHint", "ownerShowHint", "hintVisible", "ownerHint"

KeyDown CODE, KEY, MOD, REPEAT
    Sent to the focused widget when the user presses a key. CODE contains an eventual character code, KEY is one of "kb::XXX" constants, MOD is a combination of the modificator keys pressed when the event occurred ( "km::XXX" ). REPEAT is how many times the key was pressed; usually it is 1. ( see "::briefKeys" ).

    The valid "km::" constants are:

       km::Shift
       km::Ctrl
       km::Alt
       km::KeyPad
       km::DeadKey

    The valid "kb::" constants are grouped in several sets. Some codes are aliased, like, "kb::PgDn" and "kb::PageDown".

    Modificator keys
           kb::ShiftL   kb::ShiftR   kb::CtrlL      kb::CtrlR
           kb::AltL     kb::AltR     kb::MetaL      kb::MetaR
           kb::SuperL   kb::SuperR   kb::HyperL     kb::HyperR
           kb::CapsLock kb::NumLock  kb::ScrollLock kb::ShiftLock

    Keys with character code defined
           kb::Backspace  kb::Tab    kb::Linefeed   kb::Enter
           kb::Return     kb::Escape kb::Esc        kb::Space

    Function keys
           kb::F1 .. kb::F30
           kb::L1 .. kb::L10
           kb::R1 .. kb::R10

    Other
           kb::Clear    kb::Pause   kb::SysRq  kb::SysReq
           kb::Delete   kb::Home    kb::Left   kb::Up
           kb::Right    kb::Down    kb::PgUp   kb::Prior
           kb::PageUp   kb::PgDn    kb::Next   kb::PageDown
           kb::End      kb::Begin   kb::Select kb::Print
           kb::PrintScr kb::Execute kb::Insert kb::Undo
           kb::Redo     kb::Menu    kb::Find   kb::Cancel
           kb::Help     kb::Break   kb::BackTab

    See also: "KeyUp", "briefKeys", "key_down", "help", "popup", "tabOrder", "tabStop", "accelTable"

KeyUp CODE, KEY, MOD
    Sent to the focused widget when the user releases a key. CODE contains an eventual character code, KEY is one of "kb::XXX" constants, MOD is a combination of the modificator keys pressed when the event occurred ( "km::XXX" ).

    See also: "KeyDown", "key_up"

Leave
    Called when the input focus is removed from a widget

    See also: "Enter", "focused", "selected"

Menu MENU VAR_NAME
    Called before the user-navigated menu ( pop-up or pull-down ) is about to show another level of submenu on the screen. MENU is Prima::AbstractMenu descendant, that children to a widget, and VAR_NAME is the name of the menu item that is about to be shown.

    Used for making changes in the menu structures dynamically.

    See also: "popupItems"

MouseClick BUTTON, MOD, X, Y, DOUBLE_CLICK
    Called when a mouse click ( button is pressed, and then released within system-defined interval of time ) is happened in the widget area. BUTTON is one of "mb::XXX" constants, MOD is a combination of "km::XXX" constants, reflecting pressed modificator keys during the event, X and Y are the mouse pointer coordinates. DOUBLE_CLICK is a boolean flag, set to 1 if it was a double click, 0 if a single.

    "mb::XXX" constants are:

       mb::b1 or mb::Left
       mb::b2 or mb::Middle
       mb::b3 or mb::Right
       mb::b4
       mb::b5
       mb::b6
       mb::b7
       mb::b8

    See also: "MouseDown", "MouseUp", "MouseWheel", "MouseMove", "MouseEnter", "MouseLeave"

MouseDown BUTTON, MOD, X, Y
    Occurs when the user presses mouse button on a widget. BUTTON is one of "mb::XXX" constants, MOD is a combination of "km::XXX" constants, reflecting the pressed modificator keys during the event, X and Y are the mouse pointer coordinates.

    See also: "MouseUp", "MouseClick", "MouseWheel", "MouseMove", "MouseEnter", "MouseLeave"

MouseEnter MOD, X, Y
    Occurs when the mouse pointer is entered the area occupied by a widget ( without mouse button pressed ). MOD is a combination of "km::XXX" constants, reflecting the pressed modificator keys during the event, X and Y are the mouse pointer coordinates.

    See also: "MouseDown", "MouseUp", "MouseClick", "MouseWheel", "MouseMove", "MouseLeave"

MouseLeave
    Occurs when the mouse pointer is driven off the area occupied by a widget ( without mouse button pressed ).

    See also: "MouseDown", "MouseUp", "MouseClick", "MouseWheel", "MouseMove", "MouseEnter"

MouseMove MOD, X, Y
    Occurs when the mouse pointer is transported over a widget. MOD is a combination of "km::XXX" constants, reflecting the pressed modificator keys during the event, X and Y are the mouse pointer coordinates.

    See also: "MouseDown", "MouseUp", "MouseClick", "MouseWheel", "MouseEnter", "MouseLeave"

MouseUp BUTTON, MOD, X, Y
    Occurs when the user depresses mouse button on a widget. BUTTON is one of "mb::XXX" constants, MOD is a combination of "km::XXX" constants, reflecting the pressed modificator keys during the event, X and Y are the mouse pointer coordinates.

    See also: "MouseDown", "MouseClick", "MouseWheel", "MouseMove", "MouseEnter", "MouseLeave"

MouseWheel MOD, X, Y, Z
    Occurs when the user rotates mouse wheel on a widget. MOD is a combination of "km::XXX" constants, reflecting the pressed modificator keys during the event, X and Y are the mouse pointer coordinates. Z is the virtual coordinate of a wheel. Typical ( 2001 A.D. ) mouse produces Z 120-fold values.

    See also: "MouseDown", "MouseUp", "MouseClick", "MouseMove", "MouseEnter", "MouseLeave"

Move OLD_X, OLD_Y, NEW_X, NEW_Y
    Triggered when widget changes its position relative to its parent, either by Prima::Widget methods or by the user. OLD_X and OLD_Y are the old coordinates of a widget, NEW_X and NEW_Y are the new ones.

    See also: "Size", "origin", "growMode", "centered", "clipOwner"

Paint CANVAS
    Caused when the system calls for the refresh of a graphic context, associated with a widget. CANVAS is the widget itself, however its usage instead of widget is recommended ( see "Graphic content" ).

    See also: "repaint", "syncPaint", "get_invalid_rect", "scroll", "colorIndex", "font"

Popup BY_MOUSE, X, Y
    Called by the system when the user presses a key or mouse combination defined for a context pop-up menu execution. By default executes the associated Prima::Popup object, if it is present. If the event flag is cleared during the execution of callbacks, the pop-up menu is not shown.

    See also: "popup"

Setup
    This message is posted right after "Create" notification, and comes first from the event loop. Prima::Widget does not use it.

Show
    Triggered by a successive visible(1) call

    See also: "Show", "visible", "showing", "exposed"

Size OLD_WIDTH, OLD_HEIGHT, NEW_WIDTH, NEW_HEIGHT
    Triggered when widget changes its size, either by Prima::Widget methods or by the user. OLD_WIDTH and OLD_HEIGHT are the old extensions of a widget, NEW_WIDTH and NEW_HEIGHT are the new ones.

    See also: "Move", "origin", "size", "growMode", "sizeMax", "sizeMin", "rect", "clipOwner"

TranslateAccel CODE, KEY, MOD
    A distributed "KeyDown" event. Traverses all the object tree that the widget which received original "KeyDown" event belongs to. Once the event flag is cleared, the iteration stops.

    Used for tracking keyboard events by out-of-focus widgets.

    See also: "KeyDown"

ZOrderChanged
    Triggered when a widget changes its stacking order, or Z-order among its siblings, either by Prima::Widget methods or by the user.

    See also: "bring_to_front", "insert_behind", "send_to_back"

AUTHOR
Dmitry Karasik, <dmitry@karasik.eu.org>.

SEE ALSO
Prima, Prima::Object, Prima::Drawable.