    indexing
    	description: "[
    		A tree which displays a check box to left
    		hand side of each item contained. Implementation interface.
    	]"
    	legal: "See notice at end of class."
    	status: "See notice at end of class."
    	date: "$Date: 2006-01-22 18:25:44 -0800 (Sun, 22 Jan 2006) $"
    	revision: "$Revision: 56675 $"

    deferred class interface
    	EV_CHECKABLE_TREE_I

    feature -- Access

    	accept_cursor: EV_POINTER_STYLE
    			-- Accept cursor set by user.
    			-- To be displayed when the screen pointer is over a target that accepts
    			-- pebble during pick and drop.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	actual_drop_target_agent: FUNCTION [ANY, TUPLE [INTEGER_32, INTEGER_32], EV_ABSTRACT_PICK_AND_DROPABLE]
    			-- Overrides default drop target on a certain position.
    			-- If `Void', will use the default drop target.
    			-- Always void if `Current' is not a widget.
    			-- (from EV_WIDGET_I)

    	background_color: EV_COLOR
    			-- Color displayed behind foregournd features.
    			-- (from EV_COLORIZABLE_I)

    	checked_items: ARRAYED_LIST [EV_TREE_NODE]
    			-- All items checked in `Current'.
    		ensure
    			result_not_void: Result /= Void

    	cursor: EV_DYNAMIC_LIST_CURSOR [EV_TREE_NODE]
    			-- Current cursor position.
    			-- (from EV_DYNAMIC_LIST_I)
    		ensure -- from EV_DYNAMIC_LIST_I
    			not_void: Result /= Void

    	default_key_processing_handler: PREDICATE [ANY, TUPLE [EV_KEY]]
    			-- Agent used to determine whether the default key processing should occur for `Current'.
    			-- If agent returns `True' then default key processing continues as normal, False prevents
    			-- default key processing from occuring.
    			-- (from EV_WIDGET_I)

    	deny_cursor: EV_POINTER_STYLE
    			-- Deny cursor set by user.
    			-- To be displayed when the screen pointer is not over a valid target.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	foreground_color: EV_COLOR
    			-- Color of foreground features like text.
    			-- (from EV_COLORIZABLE_I)

    	generating_type: STRING_8
    			-- Name of current object's generating type
    			-- (type of which it is a direct instance)
    			-- (from ANY)

    	generator: STRING_8
    			-- Name of current object's generating class
    			-- (base class of the type of which it is a direct instance)
    			-- (from ANY)

    	help_context: FUNCTION [ANY, TUPLE, EV_HELP_CONTEXT]
    			-- Agent that evaluates to help context sent to help engine when help is requested
    			-- (from EV_HELP_CONTEXTABLE_I)
    		ensure -- from EV_HELP_CONTEXTABLE_I
    			current_if_exists: internal_help_context /= Void implies Result = internal_help_context

    	i_th (i: INTEGER_32): EV_TREE_NODE
    			-- Item at `i'-th position.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			i_within_bounds: i > 0 and then i <= count
    		ensure -- from EV_DYNAMIC_LIST_I
    			not_void: Result /= Void

    	index: INTEGER_32
    			-- Index of current position
    			-- (from EV_DYNAMIC_LIST_I)

    	index_of (v: like item; i: INTEGER_32): INTEGER_32
    			-- Index of i_th item `v', if present.
    			-- As dynamic list descendants are all sets,
    			-- Result will be zero for all values of `i'
    			-- that are not equal to one
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			positive_occurances: i > 0

    	internal_pointer_style: EV_POINTER_STYLE
    			-- Cursor displayed when screen pointer is over current widget,
    			-- as seen from interface.
    			-- (from EV_WIDGET_I)

    	is_dock_executing: BOOLEAN
    			-- Is `Current' in the process of a dockable transport?
    			-- (from EV_DOCKABLE_SOURCE_I)

    	is_dockable: BOOLEAN
    			-- Is `Current' dockable?
    			-- (from EV_DOCKABLE_SOURCE_I)

    	is_external_docking_enabled: BOOLEAN
    			-- Is `Current' able to be docked into an EV_DOCKABLE_DIALOG
    			-- When there is no valid EV_DRAGABLE_TARGET upon completion
    			-- of the transport?
    			-- (from EV_DOCKABLE_SOURCE_I)

    	is_external_docking_relative: BOOLEAN
    			-- Will dockable dialog displayed when `Current' is docked externally
    			-- be displayed relative to parent window of `Current'?
    			-- Otherwise displayed as a standard window.
    			-- (from EV_DOCKABLE_SOURCE_I)

    	is_item_checked (tree_item: EV_TREE_NODE): BOOLEAN
    			-- Is `tree_item' currently checked?

    	item: EV_TREE_NODE
    			-- Current item
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			readable: index > 0 and then index <= count
    		ensure -- from EV_DYNAMIC_LIST_I
    			not_void: Result /= Void

    	item_by_data (data: ANY): like item
    			-- First item with `data'.
    			-- (from EV_ITEM_LIST_I)
    		require -- from EV_ITEM_LIST_I
    			data_not_void: data /= Void

    	not_external_docking_enabled: BOOLEAN
    			-- Attribute used for `is_externally_dockable'. We must implement
    			-- `is_externally_dockable' this way as we have no easy solution to
    			-- assign `True' to `is_externally_dockable'.
    			-- (from EV_DOCKABLE_SOURCE_I)

    	not_is_external_docking_relative: BOOLEAN
    			-- Will dockable dialog displayed when `Current' is docked externally
    			-- be displayed relative to parent window of `Current'?
    			-- Otherwise displayed as a standard window.
    			-- Internal reversed value of is_external_docking_relative as we cannot
    			-- easily initialize a BOOLE to True in this case.
    			-- (from EV_DOCKABLE_SOURCE_I)

    	off: BOOLEAN
    			-- Is there no current item?
    			-- (from EV_DYNAMIC_LIST_I)

    	original_parent_position: INTEGER_32
    			-- Original position in parent. Required
    			-- to restore widget later.
    			-- (from EV_DOCKABLE_SOURCE_I)

    	parent: EV_CONTAINER
    			-- Container widget that contains `Current'.
    			-- (Void if `Current' is not in a container)
    			-- (from EV_WIDGET_I)

    	pebble: ANY
    			-- Data to be transported by pick and drop mechanism.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	pebble_function: FUNCTION [ANY, TUPLE, ANY]
    			-- Returns data to be transported by pick and drop mechanism.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	pebble_positioning_enabled: BOOLEAN
    			-- If `True' then pick and drop start coordinates are
    			-- pebble_x_position, pebble_y_position.
    			-- If `False' then pick and drop start coordinates are
    			-- the pointer coordinates.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	pebble_x_position: INTEGER_32
    			-- Initial x position for pick and drop relative to `Current'.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	pebble_y_position: INTEGER_32
    			-- Initial y position for pick and drop relative to `Current'.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	pixmaps_height: INTEGER_32
    			-- Height of displayed pixmaps in `Current'.
    			-- (from EV_ITEM_PIXMAP_SCALER_I)

    	pixmaps_width: INTEGER_32
    			-- Width of displayed pixmaps in `Current'.
    			-- (from EV_ITEM_PIXMAP_SCALER_I)

    	pointer_position: EV_COORDINATE
    			-- Position of the screen pointer relative to `Current'.
    			-- (from EV_WIDGET_I)
    		ensure -- from EV_WIDGET_I
    			result_not_void: Result /= Void

    	pointer_style: EV_POINTER_STYLE
    			-- Cursor displayed when screen pointer is over current widget.
    			-- Void if none has been set using `set_pointer_position'.
    			-- (from EV_WIDGET_I)

    	real_source: EV_DOCKABLE_SOURCE
    			-- `Result' is EV_DOCKABLE_SOURCE which should be
    			-- dragged when docking begins on `Current'.
    			-- (from EV_DOCKABLE_SOURCE_I)

    	real_target: EV_DOCKABLE_TARGET
    			-- `Result' is target used during a dockable transport if
    			-- mouse pointer is above `Current'.
    			-- (from EV_WIDGET_I)

    	retrieve_item_by_data (data: ANY; should_compare_objects: BOOLEAN): EV_TREE_NODE
    			-- `Result' is first item in `Current' with data
    			-- matching `some_data'. Compare objects if
    			-- `should_compare_objects' otherwise compare references.
    			-- (from EV_DYNAMIC_LIST_I)

    	retrieve_items_by_data (data: ANY; should_compare_objects: BOOLEAN): ARRAYED_LIST [EV_TREE_NODE]
    			-- `Result' is all items in `Current' with data
    			-- matching `some_data'. Compare objects if
    			-- `should_compare_objects' otherwise compare references.
    			-- (from EV_DYNAMIC_LIST_I)

    	selected_item: EV_TREE_NODE
    			-- Currently selected tree item.
    			-- (from EV_TREE_I)

    	tooltip: STRING_32
    			-- Tooltip displayed on `Current'.
    			-- (from EV_TOOLTIPABLE_I)

    feature -- Measurement

    	count: INTEGER_32
    			-- Number of items.
    			-- (from EV_DYNAMIC_LIST_I)

    	height: INTEGER_32
    			-- Vertical size in pixels.
    			-- (from EV_POSITIONED_I)

    	minimum_height: INTEGER_32
    			-- Minimum vertical size in pixels.
    			-- (from EV_POSITIONED_I)

    	minimum_width: INTEGER_32
    			-- Minimum horizontal size in pixels.
    			-- (from EV_POSITIONED_I)

    	screen_x: INTEGER_32
    			-- Horizontal offset relative to screen.
    			-- (from EV_WIDGET_I)

    	screen_y: INTEGER_32
    			-- Vertical offset relative to screen.
    			-- (from EV_WIDGET_I)

    	width: INTEGER_32
    			-- Horizontal size in pixels.
    			-- (from EV_POSITIONED_I)

    	x_position: INTEGER_32
    			-- Horizontal offset relative to parent x_position in pixels.
    			-- (from EV_POSITIONED_I)

    	y_position: INTEGER_32
    			-- Vertical offset relative to parent y_position in pixels.
    			-- (from EV_POSITIONED_I)

    feature -- Comparison

    	frozen deep_equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void
    			-- or attached to isomorphic object structures?
    			-- (from ANY)
    		ensure -- from ANY
    			shallow_implies_deep: standard_equal (some, other) implies Result
    			both_or_none_void: (some = Void) implies (Result = (other = Void))
    			same_type: (Result and (some /= Void)) implies some.same_type (other)
    			symmetric: Result implies deep_equal (other, some)

    	frozen equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void or attached
    			-- to objects considered equal?
    			-- (from ANY)
    		ensure -- from ANY
    			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

    	is_equal (other: like Current): BOOLEAN
    			-- Is `other' attached to an object considered
    			-- equal to current object?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			symmetric: Result implies other.is_equal (Current)
    			consistent: standard_is_equal (other) implies Result

    	frozen standard_equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void or attached to
    			-- field-by-field identical objects of the same type?
    			-- Always uses default object comparison criterion.
    			-- (from ANY)
    		ensure -- from ANY
    			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

    	frozen standard_is_equal (other: like Current): BOOLEAN
    			-- Is `other' attached to an object of the same type
    			-- as current object, and field-by-field identical to it?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			same_type: Result implies same_type (other)
    			symmetric: Result implies other.standard_is_equal (Current)

    feature -- Status report

    	closest_dockable_target: EV_DOCKABLE_TARGET
    			-- `Result' is first dockable target that is_dockable found by recursively
    			-- searching up through the parenting structure from the widget
    			-- currently underneath the pointer position.
    			-- `Result' will be `Void' if a dockable target is not found.
    			-- (from EV_DOCKABLE_SOURCE_I)
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			result_is_dockable: Result /= Void implies Result.is_docking_enabled

    	conforms_to (other: ANY): BOOLEAN
    			-- Does type of current object conform to type
    			-- of `other' (as per Eiffel: The Language, chapter 13)?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void

    	ensure_item_visible (an_item: EV_TREE_NODE)
    			-- Ensure `an_item' is visible in `Current'.
    			-- Tree nodes may be expanded to achieve this.
    			-- (from EV_TREE_I)

    	find_item_recursively_by_data (data: ANY): EV_TREE_NODE
    			-- If `data' contained in a tree item at any level then
    			-- assign this item to `Result'.
    			-- (from EV_TREE_NODE_LIST_I)
    		ensure -- from EV_TREE_NODE_LIST_I
    			index_not_changed: old interface.index = interface.index

    	get_next_target (a_widget: EV_WIDGET): EV_DOCKABLE_TARGET
    			-- `Result' is next dockable target that is is_dockable found by
    			-- recursively seraching up the parenting structure from `current_target'.
    			-- `Result' will be `Void' if none.
    			-- (from EV_DOCKABLE_SOURCE_I)
    		require -- from EV_DOCKABLE_SOURCE_I
    			a_widget_not_void: a_widget /= Void
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			result_is_dockable: Result /= Void implies Result.is_docking_enabled

    	has (v: like item): BOOLEAN
    			-- Does structure contain `v'?
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void

    	has_recursively (an_item: like item): BOOLEAN
    			-- Does `Current' contain `an_item' at any level?
    			-- (from EV_TREE_NODE_LIST_I)
    		ensure -- from EV_TREE_NODE_LIST_I
    			index_not_changed: old interface.index = interface.index

    	internal_non_sensitive: BOOLEAN
    			-- Is `Current' not sensitive to input as seen
    			-- from interface?
    			-- (from EV_SENSITIVE_I)

    	is_transport_enabled: BOOLEAN
    			-- Is the transport mechanism enabled?
    			-- (from EV_PICK_AND_DROPABLE_I)

    	mode_is_drag_and_drop: BOOLEAN
    			-- Is the transport mechanism drag and drop?
    			-- (from EV_PICK_AND_DROPABLE_I)

    	mode_is_pick_and_drop: BOOLEAN
    			-- Is the transport mechanism pick and drop?
    			-- (from EV_PICK_AND_DROPABLE_I)

    	mode_is_target_menu: BOOLEAN
    			-- Is the transport mechanism target menu?
    			-- (from EV_PICK_AND_DROPABLE_I)

    	recursive_do_all (action: PROCEDURE [ANY, TUPLE [EV_TREE_NODE]])
    			-- Apply `action' to every item.
    			-- Semantics not guaranteed if `action' changes the structure;
    			-- (from EV_TREE_NODE_LIST_I)

    	retrieve_item_recursively_by_data (data: ANY; should_compare_objects: BOOLEAN): EV_TREE_NODE
    			-- If `data' contained in a tree item at any level then
    			-- assign this item to `Result'. Compare objects if
    			-- `should_compare_objects' otherwise compare references.
    			-- (from EV_TREE_NODE_LIST_I)
    		ensure -- from EV_TREE_NODE_LIST_I
    			index_not_changed: old interface.index = interface.index

    	retrieve_items_recursively_by_data (data: ANY; should_compare_objects: BOOLEAN): ARRAYED_LIST [EV_TREE_NODE]
    			-- `Result' is all tree items contained in `Current' at any level,
    			-- with data matching `data'. Compare objects if
    			-- `should_compare_objects' otherwise compare references.
    			-- (from EV_TREE_NODE_LIST_I)
    		ensure -- from EV_TREE_NODE_LIST_I
    			result_not_void: Result /= Void

    	same_type (other: ANY): BOOLEAN
    			-- Is type of current object identical to type of `other'?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			definition: Result = (conforms_to (other) and other.conforms_to (Current))

    	selected: BOOLEAN
    			-- Is at least one tree item selected?
    			-- (from EV_TREE_I)

    	user_is_sensitive: BOOLEAN
    			-- Is the object sensitive to user input.
    			-- (from EV_SENSITIVE_I)

    	valid_cursor (p: CURSOR): BOOLEAN
    			-- Can the cursor be moved to position `p'?
    			-- This is True if `p' conforms to EV_DYNAMIC_LIST_CURSOR and
    			-- if it points to an item, `Current' must have it.
    			-- (from EV_DYNAMIC_LIST_I)

    feature -- Status setting

    	check_item (tree_item: EV_TREE_NODE)
    			-- Ensure check associated with `tree_item' is
    			-- checked.
    		ensure
    			item_is_checked: is_item_checked (tree_item)

    	disable_dockable
    			-- Ensure `Current' is not dockable
    			-- (from EV_DOCKABLE_SOURCE_I)
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			not_is_dockable: not is_dockable

    	disable_external_docking
    			-- Forbid `Current' to be docked into an EV_DOCKABLE_DIALOG
    			-- When there is no valid EV_DRAGABLE_TARGET upon completion
    			-- of the transport?
    			-- (from EV_DOCKABLE_SOURCE_I)
    		require -- from EV_DOCKABLE_SOURCE_I
    			is_dockable: is_dockable
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			not_externally_dockable: not is_external_docking_enabled

    	disable_external_docking_relative
    			-- Assign `False' to is_external_docking_relative, ensuring that
    			-- a dockable dialog displayed when `Current' is docked externally
    			-- is displayed as a standard window.
    			-- (from EV_DOCKABLE_SOURCE_I)
    		require -- from EV_DOCKABLE_SOURCE_I
    			external_docking_enabled: is_external_docking_enabled
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			external_docking_not_relative: not is_external_docking_relative

    	disable_pebble_positioning
    			-- Assign `False' to pebble_positioning_enabled.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	disable_transport
    			-- Deactivate pick/drag and drop mechanism.
    			-- (from EV_PICK_AND_DROPABLE_I)
    		ensure -- from EV_PICK_AND_DROPABLE_I
    			is_transport_disabled: not is_transport_enabled

    	enable_dockable
    			-- Allow `Current' to be dockable
    			-- (from EV_DOCKABLE_SOURCE_I)
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			is_dockable: is_dockable

    	enable_external_docking
    			-- Allow `Current' to be docked into an EV_DOCKABLE_DIALOG
    			-- When there is no valid EV_DRAGABLE_TARGET upon completion
    			-- of the transport?
    			-- (from EV_DOCKABLE_SOURCE_I)
    		require -- from EV_DOCKABLE_SOURCE_I
    			is_dockable: is_dockable
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			is_externally_dockable: is_external_docking_enabled

    	enable_external_docking_relative
    			-- Assign `True' to is_external_docking_relative, ensuring that
    			-- a dockable dialog displayed when `Current' is docked externally
    			-- is displayed relative to the top level window.
    			-- (from EV_DOCKABLE_SOURCE_I)
    		require -- from EV_DOCKABLE_SOURCE_I
    			external_docking_enabled: is_external_docking_enabled
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			external_docking_not_relative: is_external_docking_relative

    	enable_pebble_positioning
    			-- Assign `True' to pebble_positioning_enabled.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	enable_transport
    			-- Activate pick/drag and drop mechanism.
    			-- (from EV_PICK_AND_DROPABLE_I)
    		require -- from EV_PICK_AND_DROPABLE_I
    			pebble_not_void: pebble /= Void or pebble_function /= Void
    		ensure -- from EV_PICK_AND_DROPABLE_I
    			is_transport_enabled: interface.implementation.is_transport_enabled

    	hide
    			-- Request that `Current' not be displayed when its parent is.
    			-- (from EV_WIDGET_I)

    	internal_disable_dockable
    			-- Platform specific implementation of disable_dockable.
    			-- (from EV_DOCKABLE_SOURCE_I)

    	internal_enable_dockable
    			-- Platform specific implementation of enable_dockable.
    			-- (from EV_DOCKABLE_SOURCE_I)

    	remove_default_key_processing_handler
    			-- Ensure default_key_processing_handler is Void.
    			-- (from EV_WIDGET_I)
    		ensure -- from EV_WIDGET_I
    			default_key_processing_handler_removed: default_key_processing_handler = Void

    	remove_pebble
    			-- Remove pebble.
    			-- (from EV_PICK_AND_DROPABLE_I)
    		ensure -- from EV_PICK_AND_DROPABLE_I
    			pebble_removed: pebble = Void and pebble_function = Void
    			is_transport_disabled: not is_transport_enabled

    	remove_real_source
    			-- Ensure real_source is `Void'.
    			-- (from EV_DOCKABLE_SOURCE_I)
    		require -- from EV_DOCKABLE_SOURCE_I
    			is_dockable: is_dockable
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			real_source_void: real_source = Void

    	remove_real_target
    			-- Ensure real_target is `Void'.
    			-- (from EV_WIDGET_I)
    		ensure -- from EV_WIDGET_I
    			real_target_void: real_target = Void

    	set_accept_cursor (a_cursor: like accept_cursor)
    			-- Set `a_cursor' to be displayed when the screen pointer is over a
    			-- target that accepts pebble during pick and drop.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	set_actual_drop_target_agent (an_agent: like actual_drop_target_agent)
    			-- Assign `an_agent' to actual_drop_target_agent.
    			-- (from EV_WIDGET_I)
    		require -- from EV_WIDGET_I
    			an_agent_not_void: an_agent /= Void
    		ensure -- from EV_WIDGET_I
    			assigned: actual_drop_target_agent = an_agent

    	set_default_colors
    			-- Set foreground and background color to their default values.
    			-- (from EV_COLORIZABLE_I)

    	set_default_key_processing_handler (a_handler: like default_key_processing_handler)
    			-- Assign default_key_processing_handler to `a_handler'.
    			-- (from EV_WIDGET_I)

    	set_deny_cursor (a_cursor: like deny_cursor)
    			-- Set `a_cursor' to be displayed when the screen pointer is over a
    			-- target that doesn't accept pebble during pick and drop.
    			-- (from EV_PICK_AND_DROPABLE_I)

    	set_drag_and_drop_mode
    			-- Set transport mechanism to drag and drop,
    			-- (from EV_PICK_AND_DROPABLE_I)
    		ensure -- from EV_PICK_AND_DROPABLE_I
    			mode_is_drag_and_drop: mode_is_drag_and_drop

    	set_focus
    			-- Grab keyboard focus.
    			-- (from EV_WIDGET_I)

    	set_pebble (a_pebble: like pebble)
    			-- Assign `a_pebble' to pebble.
    			-- (from EV_PICK_AND_DROPABLE_I)
    		require -- from EV_PICK_AND_DROPABLE_I
    			a_pebble_not_void: a_pebble /= Void
    		ensure -- from EV_PICK_AND_DROPABLE_I
    			pebble_assigned: interface.implementation.pebble = a_pebble
    			is_transport_enabled: interface.implementation.is_transport_enabled

    	set_pebble_function (a_function: FUNCTION [ANY, TUPLE, ANY])
    			-- Assign `a_function' to pebble_function.
    			-- (from EV_PICK_AND_DROPABLE_I)
    		require -- from EV_PICK_AND_DROPABLE_I
    			a_function_not_void: a_function /= Void
    		ensure -- from EV_PICK_AND_DROPABLE_I
    			pebble_function_assigned: interface.implementation.pebble_function = a_function
    			is_transport_enabled: interface.implementation.is_transport_enabled

    	set_pebble_position (a_x, a_y: INTEGER_32)
    			-- Set the initial position for pick and drop relative to `Current'.
    			-- (from EV_PICK_AND_DROPABLE_I)
    		ensure -- from EV_PICK_AND_DROPABLE_I
    			pick_x_assigned: pick_x = a_x
    			pick_y_assigned: pick_y = a_y

    	set_pick_and_drop_mode
    			-- Set transport mechanism to pick and drop,
    			-- (from EV_PICK_AND_DROPABLE_I)
    		ensure -- from EV_PICK_AND_DROPABLE_I
    			mode_is_pick_and_drop: mode_is_pick_and_drop

    	set_pixmaps_size (a_width: INTEGER_32; a_height: INTEGER_32)
    			-- Set the size of displayed pixmaps in `Current' to
    			-- `a_width' by `a_height'.
    			-- (from EV_ITEM_PIXMAP_SCALER_I)
    		ensure -- from EV_ITEM_PIXMAP_SCALER_I
    			width_set: pixmaps_width = a_width
    			height_set: pixmaps_height = a_height

    	set_real_source (dockable_source: EV_DOCKABLE_SOURCE)
    			-- Set `dockable_source' to be the widget moved when a
    			-- drag begins on `Current'.
    			-- (from EV_DOCKABLE_SOURCE_I)
    		require -- from EV_DOCKABLE_SOURCE_I
    			is_dockable: is_dockable
    			dockable_source_not_void: dockable_source /= Void
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			real_source_assigned: real_source = dockable_source

    	set_real_target (a_target: EV_DOCKABLE_TARGET)
    			-- Assign `a_target' to real_target.
    			-- (from EV_WIDGET_I)
    		require -- from EV_WIDGET_I
    			target_not_void: a_target /= Void
    		ensure -- from EV_WIDGET_I
    			assigned: real_target = a_target

    	set_target_menu_mode
    			-- Set transport mechanism to target_menu.
    			-- (from EV_PICK_AND_DROPABLE_I)
    		ensure -- from EV_PICK_AND_DROPABLE_I
    			mode_is_target_menu: mode_is_target_menu

    	show
    			-- Request that `Current' be displayed when its parent is.
    			-- (from EV_WIDGET_I)

    	uncheck_item (tree_item: EV_TREE_NODE)
    			-- Ensure check associated with `tree_item' is
    			-- unchecked.
    		ensure
    			not_item_is_checked: not is_item_checked (tree_item)

    	user_disable_sensitive
    			-- Make object desensitive to user input.
    			-- (from EV_SENSITIVE_I)
    		ensure -- from EV_SENSITIVE_I
    			is_desensitive: not user_is_sensitive

    	user_enable_sensitive
    			-- Make object sensitive to user input.
    			-- (from EV_SENSITIVE_I)
    		ensure -- from EV_SENSITIVE_I
    			is_sensitive_if_parent_sensitive: (has_parent and then parent_is_sensitive) implies interface.implementation.is_sensitive
    			is_sensitive_if_orphaned: not has_parent implies interface.implementation.is_sensitive

    feature -- Cursor movement

    	back
    			-- Move to previous item.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			not_before: index > 0

    	forth
    			-- Move cursor to next position.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			not_after: index <= count

    	go_i_th (i: INTEGER_32)
    			-- Move cursor to `i'-th position.
    			-- (from EV_DYNAMIC_LIST_I)

    	go_to (p: CURSOR)
    			-- Move cursor to position `p'.
    			-- (from EV_DYNAMIC_LIST_I)

    	move (i: INTEGER_32)
    			-- Move cursor `i' positions.
    			-- (from EV_DYNAMIC_LIST_I)

    	start
    			-- Move cursor to first position.
    			-- (from EV_DYNAMIC_LIST_I)
    		ensure -- from EV_DYNAMIC_LIST_I
    			index_on_first: index = 1

    feature -- Element change

    	append (s: SEQUENCE [EV_TREE_NODE])
    			-- Append a copy of `s'. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			sequence_not_void: s /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			count_increased: old count + s.count = count

    	extend (v: like item)
    			-- Add `v' to end. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	merge_left (other: like interface)
    			-- Merge `other' into current structure before cursor
    			-- position. Do not move cursor. Empty `other'.
    			-- (from EV_DYNAMIC_LIST_I)

    	merge_right (other: like interface)
    			-- Merge `other' into current structure after cursor
    			-- position. Do not move cursor. Empty `other'.
    			-- (from EV_DYNAMIC_LIST_I)

    	put_front (v: like item)
    			-- Add `v' at beginning. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	put_i_th (v: like item; i: INTEGER_32)
    			-- Replace item at `i'-th position by `v'.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			valid_index: i > 0 and i <= count
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	put_left (v: like item)
    			-- Add `v' to the left of cursor position. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	put_right (v: like item)
    			-- Add `v' to the right of cursor position. Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	remove_help_context
    			-- Remove key press action associated with `EV_APPLICATION.help_key'.
    			-- (from EV_HELP_CONTEXTABLE_I)
    		require -- from EV_HELP_CONTEXTABLE_I
    			help_context_not_void: help_context /= Void
    		ensure -- from EV_HELP_CONTEXTABLE_I
    			no_help_context: internal_help_context = Void

    	replace (v: like item)
    			-- Replace current item by `v'.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			writable: index > 0 and then index <= count
    			v_not_void: v /= Void
    		ensure -- from EV_DYNAMIC_LIST_I
    			has_v: has (v)

    	set_background_color (a_color: like background_color)
    			-- Assign `a_color' to foreground_color.
    			-- (from EV_COLORIZABLE_I)
    		require -- from EV_COLORIZABLE_I
    			a_color_not_void: a_color /= Void
    		ensure -- from EV_COLORIZABLE_I
    			background_color_assigned: is_initialized implies interface.implementation.background_color.is_equal (a_color)

    	set_foreground_color (a_color: like foreground_color)
    			-- Assign `a_color' to foreground_color.
    			-- (from EV_COLORIZABLE_I)
    		require -- from EV_COLORIZABLE_I
    			a_color_not_void: a_color /= Void
    		ensure -- from EV_COLORIZABLE_I
    			foreground_color_assigned: is_initialized implies interface.implementation.foreground_color.is_equal (a_color)

    	set_help_context (an_help_context: like help_context)
    			-- Assign `a_help_context' to help_context.
    			-- Assign `an_help_context' to help_context.
    			-- (from EV_HELP_CONTEXTABLE_I)
    		require -- from EV_HELP_CONTEXTABLE_I
    			an_help_context_not_void: an_help_context /= Void
    		ensure -- from EV_HELP_CONTEXTABLE_I
    			help_context_assigned: help_context.is_equal (an_help_context)

    	set_minimum_height (a_minimum_height: INTEGER_32)
    			-- Set the minimum vertical size to `a_minimum_height' in pixels.
    			-- (from EV_WIDGET_I)
    		require -- from EV_WIDGET_I
    			a_minimum_height_positive: a_minimum_height >= 0
    		ensure -- from EV_WIDGET_I
    			minimum_height_assigned: is_usable implies interface.minimum_height = a_minimum_height

    	set_minimum_size (a_minimum_width, a_minimum_height: INTEGER_32)
    			-- Set the minimum horizontal size to `a_minimum_width' in pixels.
    			-- Set the minimum vertical size to `a_minimum_height' in pixels.
    			-- (from EV_WIDGET_I)
    		require -- from EV_WIDGET_I
    			a_minimum_width_positive: a_minimum_width >= 0
    			a_minimum_height_positive: a_minimum_height >= 0
    		ensure -- from EV_WIDGET_I
    			minimum_width_assigned: is_usable implies interface.minimum_width = a_minimum_width
    			minimum_height_assigned: is_usable implies interface.minimum_height = a_minimum_height

    	set_minimum_width (a_minimum_width: INTEGER_32)
    			-- Set the minimum horizontal size to `a_minimum_width' in pixels.
    			-- (from EV_WIDGET_I)
    		require -- from EV_WIDGET_I
    			a_minimum_width_positive: a_minimum_width >= 0
    		ensure -- from EV_WIDGET_I
    			minimum_width_assigned: is_usable implies interface.minimum_width = a_minimum_width

    	set_tooltip (a_tooltip: STRING_GENERAL)
    			-- Assign `a_tooltip' to tooltip.
    			-- (from EV_TOOLTIPABLE_I)
    		require -- from EV_TOOLTIPABLE_I
    			a_tooltip_not_void: a_tooltip /= Void

    feature -- Removal

    	prune (v: like item)
    			-- Remove `v' if present. Do not move cursor, except if
    			-- cursor was on `v', move to right neighbor.
    			-- (from EV_DYNAMIC_LIST_I)
    		ensure -- from EV_DYNAMIC_LIST_I
    			cursor_not_moved: not old has (v) implies old interface.index = interface.index
    			cursor_not_moved: old has (v) and then old interface.index < old index_of (v, 1) implies index = old index
    			cursor_not_moved: old has (v) and then old interface.index >= old index_of (v, 1) implies index = old index - 1
    			not_has_v: not has (v)

    	remove
    			-- Remove current item. Move cursor to right neighbor
    			-- (or `after' if no right neighbor).
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			writable: not off
    		ensure -- from EV_DYNAMIC_LIST_I
    			not_has_v: not has (old item)

    	remove_left
    			-- Remove item to the left of cursor position.
    			-- Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			left_exists: index > 1
    			not_before: not (index = 0)
    		ensure then -- from EV_DYNAMIC_LIST_I
    			left_neighbor_removed: not has (old i_th (index - 1))

    	remove_right
    			-- Remove item to the right of cursor position.
    			-- Do not move cursor.
    			-- (from EV_DYNAMIC_LIST_I)
    		require -- from EV_DYNAMIC_LIST_I
    			right_exists: index < count
    		ensure then -- from EV_DYNAMIC_LIST_I
    			right_neighbor_removed: not has (old i_th (index + 1))

    	wipe_out
    			-- Remove all items.
    			-- (from EV_DYNAMIC_LIST_I)

    feature -- Duplication

    	copy (other: like Current)
    			-- Update current object using fields of object attached
    			-- to `other', so as to yield equal objects.
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    			type_identity: same_type (other)
    		ensure -- from ANY
    			is_equal: is_equal (other)

    	frozen deep_copy (other: like Current)
    			-- Effect equivalent to that of:
    			--		copy (`other' . deep_twin)
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			deep_equal: deep_equal (Current, other)

    	frozen deep_twin: like Current
    			-- New object structure recursively duplicated from Current.
    			-- (from ANY)
    		ensure -- from ANY
    			deep_equal: deep_equal (Current, Result)

    	frozen standard_copy (other: like Current)
    			-- Copy every field of `other' onto corresponding field
    			-- of current object.
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    			type_identity: same_type (other)
    		ensure -- from ANY
    			is_standard_equal: standard_is_equal (other)

    	frozen standard_twin: like Current
    			-- New object field-by-field identical to `other'.
    			-- Always uses default copying semantics.
    			-- (from ANY)
    		ensure -- from ANY
    			standard_twin_not_void: Result /= Void
    			equal: standard_equal (Result, Current)

    	frozen twin: like Current
    			-- New object equal to `Current'
    			-- twin calls copy; to change copying/twining semantics, redefine copy.
    			-- (from ANY)
    		ensure -- from ANY
    			twin_not_void: Result /= Void
    			is_equal: Result.is_equal (Current)

    feature -- Basic operations

    	close_dockable_dialog (dockable_dialog: EV_DOCKABLE_DIALOG)
    			-- Close request received by `dockable_dialog' so
    			-- restore widget contained back to its original position
    			-- in its old parent if possible.
    			-- We must fire `dock_ended' actions.
    			-- (from EV_DOCKABLE_SOURCE_I)
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			dockable_dialog_destroyed: dockable_dialog.is_destroyed

    	complete_dock
    			-- Complete a dock from source_being_docked.
    			-- (from EV_DOCKABLE_SOURCE_I)
    		require -- from EV_DOCKABLE_SOURCE_I
    			source_being_docked: source_being_docked /= Void
    		ensure -- from EV_DOCKABLE_SOURCE_I
    			not_dock_executing: not is_dock_executing
    			insert_separator_not_parented: insert_sep.parent = Void
    			insert_label_not_parented: insert_label.parent = Void

    	frozen default: like Current
    			-- Default value of object's type
    			-- (from ANY)

    	frozen default_pointer: POINTER
    			-- Default value of type `POINTER'
    			-- (Avoid the need to write `p'.default for
    			-- some `p' of type `POINTER'.)
    			-- (from ANY)

    	default_rescue
    			-- Process exception for routines with no Rescue clause.
    			-- (Default: do nothing.)
    			-- (from ANY)

    	frozen do_nothing
    			-- Execute a null action.
    			-- (from ANY)

    	refresh_now
    			-- Force an immediate redraw of `Current'.
    			-- (from EV_WIDGET_I)

    feature -- Inapplicable

    	drag_cursor: EV_POINTER_STYLE
    			-- Cursor used when `Current' is being transported.
    			-- (from EV_DOCKABLE_SOURCE_I)

    feature -- Access EV_DRAGABLE_SOURCE.

    	dockable_dialog_target: EV_DOCKABLE_DIALOG
    			-- A dockable dialog that will be created as
    			-- necessary. This is not a local, to avoid it
    			-- being garbage collected.
    			-- (from EV_SHARED_TRANSPORT_I)

    	global_drag_targets: ARRAYED_LIST [INTEGER_32]
    			-- Shortcut to EV_APPLICATION.pnd_targets.
    			-- (from EV_SHARED_TRANSPORT_I)

    	insert_label: EV_CELL
    			-- Label used to indicate where `Current' will be placed in target.
    			-- (from EV_SHARED_TRANSPORT_I)
    		ensure -- from EV_SHARED_TRANSPORT_I
    			result_not_void: Result /= Void

    	insert_label_imp: EV_CELL_I
    			-- Once access to implementation of Insert_label.
    			-- (from EV_SHARED_TRANSPORT_I)
    		ensure -- from EV_SHARED_TRANSPORT_I
    			Result /= Void

    	insert_sep: EV_TOOL_BAR_SEPARATOR
    			-- Once access to a separator used to indicate the insertion position
    			-- when moving tool bar items.
    			-- (from EV_SHARED_TRANSPORT_I)

    	insert_sep_imp: EV_TOOL_BAR_SEPARATOR_I
    			-- Once access to implementation of Insert_sep.
    			-- (from EV_SHARED_TRANSPORT_I)
    		ensure -- from EV_SHARED_TRANSPORT_I
    			Result /= Void

    	internal_screen: EV_SCREEN
    			-- Once access to an EV_SCREEN.
    			-- (from EV_SHARED_TRANSPORT_I)

    	original_x_offset: INTEGER_16
    			-- Original x_offset and original_y_offset of transport
    			-- realtive to widget. Only used for dragable transports.
    			-- (from EV_SHARED_TRANSPORT_I)

    	original_y_offset: INTEGER_16
    			-- Original x_offset and original_y_offset of transport
    			-- realtive to widget. Only used for dragable transports.
    			-- (from EV_SHARED_TRANSPORT_I)

    	originating_source: EV_DOCKABLE_SOURCE_I
    			-- Dragable source that originated the transport of `source_being_dragged'.
    			-- (from EV_SHARED_TRANSPORT_I)

    	remove_insert_label
    			-- Remove Insert_label from its current parent.
    			-- We must handle a special case for cells. If the parent is a cell,
    			-- then we remove the cell from its parent, and then restore it.
    			-- Otherwise, when the label, removed, the cell keeps it size, and cells
    			-- are normally used with real_target when the cell must
    			-- not be visible.
    			-- (from EV_SHARED_TRANSPORT_I)
    		ensure -- from EV_SHARED_TRANSPORT_I
    			not_parented: insert_label.parent = Void

    	remove_insert_sep
    			-- Ensure `inset_sep' is not parented.
    			-- (from EV_SHARED_TRANSPORT_I)
    		ensure -- from EV_SHARED_TRANSPORT_I
    			not_parented: insert_sep.parent = Void

    	source_being_docked: EV_DOCKABLE_SOURCE_I
    			-- Dragable source currently being transported. May be a
    			-- WIDGET_IMP or an EV_TOOL_BAR_BUTTON_IMP.
    			-- (from EV_SHARED_TRANSPORT_I)

    feature -- Access EV_PICK_AND_DROPABLE.

    	default_accept_cursor: EV_POINTER_STYLE
    			-- Used in lieu of a user defined accept_cursor.
    			-- (from EV_SHARED_TRANSPORT_I)

    	default_deny_cursor: EV_POINTER_STYLE
    			-- Used in lieu of a user defined deny_cursor.
    			-- (from EV_SHARED_TRANSPORT_I)

    	default_pixmaps: EV_STOCK_PIXMAPS
    			-- Default pixmaps
    			-- (from EV_SHARED_TRANSPORT_I)

    	global_pnd_targets: HASH_TABLE [INTEGER_32, INTEGER_32]
    			-- Shortcut to EV_APPLICATION.pnd_targets.
    			-- (from EV_SHARED_TRANSPORT_I)

    	rubber_band_is_drawn: BOOLEAN
    			-- Is a rubber band line currently on the screen?
    			-- (from EV_SHARED_TRANSPORT_I)

    feature -- Access common.

    	pointer_x: INTEGER_16
    			-- (from EV_SHARED_TRANSPORT_I)

    	pointer_y: INTEGER_16
    			-- (from EV_SHARED_TRANSPORT_I)

    feature -- Event handling

    	check_actions: EV_TREE_ITEM_CHECK_ACTION_SEQUENCE
    			-- Actions to be performed when an item is checked.
    			-- (from EV_CHECKABLE_TREE_ACTION_SEQUENCES_I)
    		ensure -- from EV_CHECKABLE_TREE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	conforming_pick_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when a pebble that fits here is picked.
    			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I)
    		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	deselect_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when a tree item is deselected.
    			-- (from EV_TREE_ACTION_SEQUENCES_I)
    		ensure -- from EV_TREE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	dock_ended_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed after a dock completes from `Current'.
    			-- Either to a dockable target or a dockable dialog.
    			-- (from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES_I)
    		ensure -- from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	dock_started_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when pebble is picked up.
    			-- (from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES_I)
    		ensure -- from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	drop_actions: EV_PND_ACTION_SEQUENCE
    			-- Actions to be performed when a pebble is dropped here.
    			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I)
    		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	file_drop_actions: ACTION_SEQUENCE [TUPLE [LIST [STRING_32]]]
    			-- Actions to be performed when an OS file drop occurs on `Current'.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	focus_in_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when keyboard focus is gained.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	focus_out_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when keyboard focus is lost.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	key_press_actions: EV_KEY_ACTION_SEQUENCE
    			-- Actions to be performed when a keyboard key is pressed.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	key_press_string_actions: EV_KEY_STRING_ACTION_SEQUENCE
    			-- Actions to be performed when a keyboard press generates a displayable character.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	key_release_actions: EV_KEY_ACTION_SEQUENCE
    			-- Actions to be performed when a keyboard key is released.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	mouse_wheel_actions: EV_INTEGER_ACTION_SEQUENCE
    			-- Actions to be performed when mouse wheel is rotated.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	pick_actions: EV_PND_START_ACTION_SEQUENCE
    			-- Actions to be performed when pebble is picked up.
    			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I)
    		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	pick_ended_actions: EV_PND_FINISHED_ACTION_SEQUENCE
    			-- Actions to be performed when a transport from `Current' ends.
    			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I)
    		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	pointer_button_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
    			-- Actions to be performed when screen pointer button is pressed.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	pointer_button_release_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
    			-- Actions to be performed when screen pointer button is released.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	pointer_double_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
    			-- Actions to be performed when screen pointer is double clicked.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	pointer_enter_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when screen pointer enters widget.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	pointer_leave_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when screen pointer leaves widget.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	pointer_motion_actions: EV_POINTER_MOTION_ACTION_SEQUENCE
    			-- Actions to be performed when screen pointer moves.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	resize_actions: EV_GEOMETRY_ACTION_SEQUENCE
    			-- Actions to be performed when size changes.
    			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
    		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	select_actions: EV_NOTIFY_ACTION_SEQUENCE
    			-- Actions to be performed when a tree item is selected.
    			-- (from EV_TREE_ACTION_SEQUENCES_I)
    		ensure -- from EV_TREE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    	uncheck_actions: EV_TREE_ITEM_CHECK_ACTION_SEQUENCE
    			-- Actions to be performed when an item is unchecked.
    			-- (from EV_CHECKABLE_TREE_ACTION_SEQUENCES_I)
    		ensure -- from EV_CHECKABLE_TREE_ACTION_SEQUENCES_I
    			not_void: Result /= Void

    feature -- Output

    	io: STD_FILES
    			-- Handle to standard file setup
    			-- (from ANY)

    	out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of tagged_out.
    			-- (from ANY)

    	print (some: ANY)
    			-- Write terse external representation of `some'
    			-- on standard output.
    			-- (from ANY)

    	frozen tagged_out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of out.
    			-- (from ANY)

    feature -- Platform

    	operating_environment: OPERATING_ENVIRONMENT
    			-- Objects available from the operating system
    			-- (from ANY)

    feature -- Status Report

    	has_capture: BOOLEAN
    			-- Does widget have capture?
    			-- (from EV_WIDGET_I)

    	has_focus: BOOLEAN
    			-- Does widget have the keyboard focus?
    			-- (from EV_WIDGET_I)

    	is_displayed: BOOLEAN
    			-- Is `Current' visible on the screen?
    			-- False if `Current' is entirely obscured by another window.
    			-- (from EV_WIDGET_I)

    	is_show_requested: BOOLEAN
    			-- Will `Current' be displayed when its parent is?
    			-- See also is_displayed.
    			-- (from EV_WIDGET_I)

    invariant
    		-- from EV_WIDGET_I
    	is_displayed_implies_show_requested: is_usable and is_displayed implies is_show_requested

    		-- from EV_PICK_AND_DROPABLE_I
    	user_interface_modes_mutually_exclusive: mode_is_pick_and_drop.to_integer + mode_is_drag_and_drop.to_integer + mode_is_target_menu.to_integer = 1
    	pebble_function_takes_two_integer_open_operands: pebble_function /= Void implies pebble_function.valid_operands ([1, 1])

    		-- from EV_ANY_I
    	interface_coupled: is_usable implies interface /= Void and then interface.implementation = Current
    	base_make_called: base_make_called

    		-- from ANY
    	reflexive_equality: standard_is_equal (Current)
    	reflexive_conformance: conforms_to (Current)

    		-- from EV_DOCKABLE_SOURCE_I
    	widget_or_item_source: not (widget_source_being_docked /= Void and item_source_being_docked /= Void)
    	dock_executing: is_dock_executing implies widget_source_being_docked /= Void or item_source_being_docked /= Void

    		-- from EV_POSITIONED_I
    	minimum_width_positive_or_zero: is_usable implies minimum_width >= 0
    	minimum_height_positive_or_zero: is_usable implies minimum_height >= 0

    		-- from EV_DYNAMIC_LIST_I
    	index_within_bounds: is_usable implies (index >= 0 and then index <= count + 1)

    indexing
    	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
    	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
    	source: "[
    		Eiffel Software
    		356 Storke Road, Goleta, CA 93117 USA
    		Telephone 805-685-1006, Fax 805-685-6869
    		Website http://www.eiffel.com
    		Customer support http://support.eiffel.com
    	]"

    end -- class EV_CHECKABLE_TREE_I