INT 6F - HP Vectra EX-BIOS - "F_IO_CTRL SF_EVENT_ON" - ENABLE EVENT HANDLER
	AX = 040Ah
	BP = driver ID (see #03741) for V_LPOINTER, V_LTOUCH, V_LTABLET
Return: AH = status (see #03744)
	BP,DS destroyed
SeeAlso: AH=00h"HP Vectra",AX=0408h"SF_CREATE_EVENT",AX=040Ch"SF_EVENT_OFF"
SeeAlso: AX=040Eh"SF_CLIPPING_ON"