This event is fired when the mouse button goes down on the control.
Use the NodeFromPoint to query which node or part was clicked.
The MouseUp event behaves like any REALbasic MouseUp event where it does not normally fire unless if true was returned from MouseDown. Note that the control it self might have returned true for MouseDown in some cases where the control internally needs the MouseUp event.
The internal handling of MouseUp can be canceled by setting the CancelEventAction property to true.
Note:
On some platforms clicking on the scrollbar will not generate a mouse up event.