XmTrackingEvent man page
XmTrackingEvent — A Toolkit function that provides a modal interaction
#include <Xm/Xm.h> Widget XmTrackingEvent( Widget widget, Cursor cursor, Boolean confine_to, XEvent *event_return);
XmTrackingEvent provides a modal interface for selection of a component. It is intended to support context help. The function calls the XmUpdateDisplay function. XmTrackingEvent then grabs the pointer and discards succeeding events until BSelect is released or a key is pressed and then released. The function then returns the widget or gadget that contains the pointer when BSelect is released or a key is released, and ungrabs the pointer.
Specifies the widget ID of a widget to use as the basis of the modal interaction. That is, the widget within which the interaction must occur, usually a top-level shell.
Specifies the cursor to be used for the pointer during the interaction. This is a standard X cursor name.
Specifies whether or not the cursor should be confined to widget.
Returns the ButtonRelease or KeyRelease event that causes the function to return.
Returns the widget or gadget that contains the pointer when BSelect is released or a key is released. If no widget or gadget contains the pointer, the function returns NULL.