--- pointer-lock.c	2011-01-30 13:01:37.396999981 +0000
+++ pointer-lock2.c	2011-01-30 13:09:44.834999934 +0000
@@ -2,6 +2,8 @@
 pointerlock(const Arg *a)
 {
 	if(a->i){
+		if(!selmon->sel)
+			return;
 		if(XGrabPointer(dpy, selmon->sel->win, False, MOUSEMASK,
 				GrabModeAsync, GrabModeAsync,
 				selmon->sel->win, None, CurrentTime) != GrabSuccess)