XmGetDestination — A function that returns the widget ID of the widget to be used as the current

XmGetDestination returns the widget that is the  current  destination  on  the  specified  display.   The
       destination is generally the last editable widget on which a select, edit, insert, or paste operation was
       performed  and  is  the  destination for quick paste and certain clipboard functions.  The destination is
       NULL until a keyboard or mouse operation has been  done  on  an  editable  widget.  Refer  to  the  MotifProgrammer'sGuide for a description of keyboard focus.

       display   Specifies the display whose destination widget is to be queried

XmGetDestination  —  A  function  that  returns  the  widget  ID  of the widget to be used as the current
       destination for quick paste and certain clipboard operations "XmGetDestination"

       Returns the widget ID for the current destination or NULL if there is no current destination.

                                                                                             XmGetDestination(3)

       #include <Xm/Xm.h>
       WidgetXmGetDestination(
       Display*display);