INT 2F - Windows 3.x (OS/2 2.x???) - GET VIRTUAL DEVICE DRIVER (VDD) CAPABLTIES
        AX = 4000h
Return: AL = 01h does not virtualize video access
             02h virtualizes the video when in text mode
             03h virtualizes the video when in text mode or single plane
                 graphics modes
             04h virtualizes the video when in text mode, single plane
                 graphics modes, and VGA multiplane modes
             FFh virtualizes the video fully
Note:   this function is used by display drivers to find out what capabilities
          exist for the VDD driver and also trigger then VDD driver to call
          functions 4005h and 4006h.  This function also gives the Video Driver
          hardware access to the video registers.