INT 62 u - FGDRIVER v4.02 - "FG_VBOPEN" - MAKE VIRTUAL BUFFER ACTIVE
	AX = 00D5h
	BX = virtual buffer handle
Return: AX = status
	    0000h successful
	    FFFEh no buffer defined for specified handle
	    FFFFh invalid buffer handle
Note:	the FGDRIVER functions are rearranged with each major release, but
	  their parameters do not change (see #03474)
SeeAlso: AX=00CDh,AX=00CEh,AX=00D1h,AX=00D4h,AX=00D9h