)
Call VioScrollDn with:
	STACK:	WORD	VIO handle (must be 00h)
		DWORD	pointer to char/attr cell for filling emptied rows
		WORD	number or rows to scroll (FFFFh = clear area)
		WORD	right column of scroll area
		WORD	bottom row of scroll area
		WORD	left column of scroll area
		WORD	top row of scroll area
Return: AX = error code (00h, 74h, 166h, 167h, 1B4h) (see #00373)
SeeAlso: #00384,INT 10/AH=07h