INT 15 - DESQview/X 1.02+ - DVDOS4GX.DVR - GET ??? MAILBOX OWNER                
	AX = BFDEh
	BX = 0017h
	CX = index of ??? mailbox
		(0000h-0004h valid, but no range checking done)
Return: AX = segment of mailbox owner's handle
	BX = segment of caller's task handle
SeeAlso: AX=BFDEh/BX=0015h,AX=BFDEh/BX=0016h