# Viewport (filter)

A Viewport is a filter that provides scrollbars (both horizontal and vertical) to let you scroll over its child-component when the child's preferred size is bigger than the Viewport's size. In much the same way as a Browser is used to view many lines of text, a Viewport can be used to see a large VBox. Also, Viewports have a mechanism for splitting into two or more views of the child.

Step
  (Cardinal, 10)
  The number of pixels to move while scrolling.

Axis choices (mutually exclusive):

Vertical
  (Boolean, `TRUE`)
  If this is true, the the typing meta-left-click in a vertical scrollbar will split the view of the adjacent window. Meta-right-click will merge two views.
Horizontal
  (Boolean, `FALSE`)
  If this is true, the the typing meta-left-click in a horizontal scrollbar will split the view of the adjacent window. Meta-right-click will merge two views.

  Scrolling choices (mutually exclusive):
HorAndVer
  (Boolean, `TRUE`)
  This puts a horizontal and vertical scrollbar on every view, and a ``reset'' button in the southwest corner that moves the northwest corner of the child to the northwest corner of the view.
HorOnly
  (Boolean, `FALSE`)
  Places a horizontal scrollbar at the bottom of the Viewport, and none at the side.
VerOnly
  (Boolean, `FALSE`)
  Places a vertical scrollbar on the left side of the Viewport, and none at the bottom.
AlaViewport
  (Boolean, `FALSE`)
  This specifies that there is a scrollbar in the same axis as the Viewport. Thus, `AlaViewport` for a vertical viewport is equivalent to `VerOnly`.
Auto
  (Boolean, `FALSE`)
  This specifies that scroll bars appear only when the preferred size of the child exceeds the size of the Viewport (along that axis).
NoScroll
  (Boolean, `FALSE`)
  This specifies that there should be no scrollbars.