--- a/src/scrollbar-x.c	Mon Aug 13 11:01:58 2007 +0200
+++ b/src/scrollbar-x.c	Mon Aug 13 11:03:08 2007 +0200
@@ -408,9 +408,6 @@
     return;
 
   mirror = find_scrollbar_window_mirror (f, id);
-  if (!mirror)
-    return;
-  
   win = real_window (mirror, 1);
 
   if (NILP (win))
@@ -614,9 +611,6 @@
     return;
 
   mirror = find_scrollbar_window_mirror (f, id);
-  if (!mirror)
-    return;
-  
   win = real_window (mirror, 1);
 
   if (NILP (win))
@@ -680,6 +674,19 @@
 		    0, (Window) NULL);
 }
 
+/* Called directly from x_any_window_to_frame in frame-x.c */
+EMACS_INT
+x_window_is_scrollbar (struct frame *f, Window win)
+{
+  if (!FRAME_X_P (f))
+    return 0;
+
+  if (f->mirror_dirty)
+    update_frame_window_mirror (f);
+  return (EMACS_INT) x_scrollbar_loop (X_WINDOW_IS_SCROLLBAR, f->root_window,
+				 f->root_mirror, 0, win);
+}
+
 /* Make sure that all scrollbars on frame are up-to-date.  Called
    directly from x_set_frame_properties in frame-x.c*/
 void