VEraseOverlayMessage - erases a 1-bit overlay message.
  Window win;
  int ovl;
  int xloc,yloc;
  char *msg;
  VEraseOverlayMessage erases a 1-bit overlay message, in the image window
or one of its subwindows. If the message is out of the window boundary, 
VEraseOverlayMessage truncates the message and returns an error code 224.
Return Value
  0 - work successfully.
  6 - invalid window ID.
  223 - message erased in the image window covered by the dialog window.
  224 - message erased is out of window boundary.
  225 - no overlay created.
  237 - the overlay is not on.
  win - the image window ID or one of its subwindows' ID.
  ovl - specifies the overlay number to be used to erase the message.
  xloc, yloc - specifies x and y coordinates of the message located.
  msg - specifies the message to be erased.
Side Effects
  Any other graphics in that overlay in that message will also be erased.
Entry Conditions
  VTurnOnOverlay should be called first. If the value xloc, yloc, or ovl is 
not valid, msg is NULL, VCreateColormap is not called earlier, or the message 
is totally out of the window boundary, VEraseOverlayMessage prints an error 
message to the standard error stream, produces a core dump file and exits from
the current process.
Related Functions
VDisplayOverlayMessage, VTurnOffOverlay, VEraseOverlay.