Int 15 Fn DE29  U - Desqview/x - ???                                       [Q]

   AX = DE29h
   BX = 0003h
   DX = segment of window handle

Return: CF clear if successful
       ???
   CF set on error

Note:  DESQview 2.50-2.52 are distributed as part of DESQview/X v1.0x.