Pull out the behaviour in grab_label and search_start into one utility

function menu_filter(). The plan is to eventually merge in grab_menu too.
Shrinks the code a fair bit.

Also, change XMaskEvent for XWindowEvent to prevent getting exposes for other
windows. This is particuarly noticable on slow machines with a LOT of xterms
(todd, you're an odd man).

ok okan@, todd@.

Makefile

@@ -4,8 +4,8 @@
 
 PROG=		cwm
 
-SRCS=		calmwm.c screen.c xmalloc.c client.c grab.c search.c \
-		util.c xutil.c conf.c input.c xevents.c group.c \
+SRCS=		calmwm.c screen.c xmalloc.c client.c grab.c menu.c \
+		search.c util.c xutil.c conf.c input.c xevents.c group.c \
 		kbfunc.c font.c parse.y
 
 CPPFLAGS+=	-I${X11BASE}/include -I${X11BASE}/include/freetype2 -I${.CURDIR}