XmClipboardUndoCopy — A clipboard function that deletes the
last item placed on the clipboard

     #include <Xm/CutPaste.h>
int XmClipboardUndoCopy (display, window)
        Display * display;
        Window  window;

     XmClipboardUndoCopy deletes the last item placed on the
clipboard if the item was placed there by an application
with the passed display and window arguments. Any data item
deleted from the clipboard by the original call to
XmClipboardCopy is restored. If the display or window IDs do
not match the last copied item, no action is taken, and this
function has no effect.

display   Specifies a pointer to the Display structure that
          was returned in a previous call to XOpenDisplay or

window    Specifies the window ID of a widget that relates
          the application window to the clipboard. The
          widget’s window ID can be obtained through
          XtWindow.  The same application instance should
          pass the same window ID to each clipboard function
          it calls.

          The function was successful.

          The function failed because the clipboard was
          locked by another application. The application can
          continue to call the function again with the same
          parameters until the lock goes away. This gives
          the application the opportunity to ask if the user
          wants to keep trying or to give up on the

     XmClipboardLock(3) and XmClipboardStartCopy(3).