INT 62 u - FGDRIVER v4.02 - "FG_GETMAXX" - GET MAXIMUM COLUMN IN SCREEN SPACE
	AX = 0049h
Return: AX = maximum X coordinate in screen space
	    (or character space if in text mode)
Note:	the FGDRIVER functions are rearranged with each major release, but
	  their parameters do not change (see #03474 at AX=0000h)
SeeAlso: AX=004Ah,AX=00C1h