Bitfields for message box flags:
Bit(s)	Description	)
 3-0	response codes (see #02565)
 7-4	icon codes
	1 = Warning hand
	2 = exclamation mark
	4 = asterisk
 9-8	default response (0 = first button, 1 = second, 2 = third)
 12	message is system model
 15	don't change focus
 29	hang with interrupts enabled
 30	do not window
 31	execute ASAP