lm_exitbutton

Add exit button to frame. By default this button is
placed in the upper right corner of a frame.

CALL:

   h = lm_exitbutton(hparent, BACKG, callback, btn)
      

INPUT:

   hparent: 
    handle van parent frame
   BACKG: 
    color for transparant part of button
   callback:
    additional function to call when frame is closed
   btn: 
    cdata
  

OUTPUT:

   h: 
    handle van button