VideoMode()

         Returns and/or changes the video mode

    Syntax:

         VideoMode( nNewMode ) -> nOldMode

         nNewMode : The new video mode.
                    01 -> 40x25
                    03 -> 80x25
                    15 -> EGA 640x350 Mono
                    16 -> EGA 640x350 Colour
                    17 -> VGA 640x480 Mono
                    18 -> VGA 640x480 Colour
                    ...

    Description:

         It returns the active video mode and optionally changes it if
         nNewMode is specified. For getting more information about the
         video modes consult the interrupts list of Ralf Brown which is
         available in almost all BBS.

    Return:

         The active video mode.

    Example:

         nOld := VideoMode ( 18 )
         DispStr ( "Hello", 10, 10, 7, 12 )
         Inkey(0)
         VideoMode ( nOld )