A toolkit function that determines which child intersects or comes closest to a specified point
#include <Xm/Xm.h> Widget XmObjectAtPoint Widget widgetPosition xPosition y
XmObjectAtPoint searches the child list of the specified manager widget and returns the child most closely associated with the specified x,y coordinate pair.
For the typical Motif manager widget, XmObjectAtPoint uses the following rules to determine the returned object:
The preceding rules are only general. In fact, each manager widget is free to define "most closely associated" as it desires. For example, if no child intersects x,y, a manager might return the child closest to x,y.
Returns the child of manager most closely associated with x,y. If none of its children are sufficiently associated with x,y, returns NULL.