INT 10 U - VIDEO - DESQview 2.0x only - internal - SET ??? HANDLER
        AH = 80h
        DX = 4456h ('DV')
        ES:DI -> FAR subroutine to be called on ???
Return: DS = segment of DESQview data structure for video buffer
Note:   this function is probably meant for internal use only, due to the magic
          value required in DX
        the subroutine seems to be called when the DESQview menu is accessed;
          on entry, AL = 03h or 04h