INT 10 - VIDEO - DOS/V - SHIFT STATUS LINE CONTROL

	AH = 1Dh
	AL = function
	    00h enable shift status line(s)
		BX = number of lines to reserve at bottom of screen (usu. 1)
	    01h disable shift status line
		BX = number of lines reserved at bottom of screen (usually 1)
	    02h get number of status lines
		Return: BX = number of lines reserved for shift status
SeeAlso: AH=19h