The WDS_ScrollRegion
widget takes advantage of the partial event usage to maximize fluidity
of the interface.
If a valid left mouse press is left unused by decendent widgets, the
WDS_ScrollRegion widget will use it as a drag of the scrollable area.
The scrollable region can consume the X and Y components of an event,
but only if they can actually be used.
This means that if the scrollable region is dragged to an edge,
the unused mouse motion can be used by an ancestor.
The middle mouse can be used for a different method of dragging.
Assuming a middle mouse event is not consumed by a decendent,
pressing the middle mouse in the scrollable region will overlay
a reduced outline of the scrollable region
and the visible sub-area within.
Motion with the middle mouse pressed will center the sub-area outline
about the mouse location.
A WDS_ScrollRegion widget creates two WDS_ScrollBar
widgets which it exclusively uses.
void AddScrollField(long direction,float start,float size)
void ClearScrollFields(long direction)
Add one or clear all scroll fields for the scroll-bar in the specified
direction,
either WDS_HORIZONTAL or WDS_VERTICAL.
See WDS_ScrollBar for an explanation of scroll fields.