Hack scrollwheel support into the eventloop, by treating button 4-5

Hack scrollwheel support into the eventloop, by treating button 4-5

Wed Jan 27 18:40:50 1999  Owen Taylor  <otaylor@redhat.com>

	* gtk/gtkmain.c (gtk_main_do_event): Hack scrollwheel
	support into the eventloop, by treating button 4-5
	presses on scrolled windows and scrollbars specially.
	Put it here to keep the ugliness small and confined.
	(We need to intercept the normal propagation in any case
	to have this work reliably right now, since some
	subwidgets will trap the button presses)

	* gtk/gtkviewport.c (gtk_viewport_realize): Select for
	BUTTON_PRESS to	support the above hack.