INT 2F - MDEBUG display driver - SAVE GRAPHIC DATA
        AX = D002h
Return: CF set on error
        CF clear if successful
            display memory saved and display switched to one of the text modes
              02h, 03h or 07h.
Note:   MDEBUG calls this function only once every popup session before
          displaying its windows.
SeeAlso: AX=D003h