INT 49 - MAGic v1.16+ - GET SIZE OF MAGNIFICATION WINDOW                        
	AX = 0007h
Return: AX = status
	    0000h successful
		BX = vertical size (char rows or pixel rows)
		DX = horizontal size (char cols or 8-pixel units)
	    FFFEh invalid function
	    FFFFh MAGic busy, retry later
		BX,DX destroyed
	CX destroyed
BUG:	in v1.16 and v1.17, this function is not recognized as valid, but
	  AX=0000h is accepted and will branch into hyperspace
SeeAlso: AX=0001h,AX=0006h