Actually my QueryUnload code looks something like:

with This
	if not .AddQueryUnload()
		NoDefault
		return
	endif
	if type(".lCanceled") = "L"
		if .lCanceled
			.RevertTables()
		else
			.UpdateTables()
		endif
	else
		.UpdateTables()
	endif
	.Release()
endwith

My Form class has a property, lCanceled that is always set to false. My Cancel button sets that property it to True if clicked. My Cancel and Exit buttons then call the form's QueryUnload. So if the user clicks the form X or the VFP app X buttons all shutdowns according to Hoyle.