[gtk+] [GdkWindowCache] Don't ignore the CompositeOverlayWindow

[Adel Gadllah <agadllah src gnome org>]

commit 85ae875dcbfcfa3fbdca857dc90467d39b9ff0c5
Author: Adel Gadllah <adel gadllah gmail com>
Date:   Mon Sep 13 18:20:22 2010 +0200

    [GdkWindowCache] Don't ignore the CompositeOverlayWindow
    
    Add the composite overlay window to the cache, as this can be a reasonable Xdnd proxy as well.
    
    This is only done when the screen is composited in order to avoid mapping
    the COW. We assume that the CM is using the COW (which is true for pretty
    much any CM currently in use).
    
    https://bugzilla.gnome.org/show_bug.cgi?id=601731

 gdk/x11/gdkdnd-x11.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+), 0 deletions(-)
---
diff --git a/gdk/x11/gdkdnd-x11.c b/gdk/x11/gdkdnd-x11.c
index fc946cb..b5e595f 100644
--- a/gdk/x11/gdkdnd-x11.c
+++ b/gdk/x11/gdkdnd-x11.c
@@ -30,6 +30,7 @@
 #include <X11/Xutil.h>
 #include <X11/Xatom.h>
 #include <X11/extensions/shape.h>
+#include <X11/extensions/Xcomposite.h>
 
 #include <string.h>
 
@@ -537,6 +538,7 @@ gdk_window_cache_new (GdkScreen *screen)
   GdkWindow *root_window = gdk_screen_get_root_window (screen);
   GdkChildInfoX11 *children;
   guint nchildren, i;
+  Window cow;
   
   GdkWindowCache *result = g_new (GdkWindowCache, 1);
 
@@ -585,6 +587,20 @@ gdk_window_cache_new (GdkScreen *screen)
 
   g_free (children);
 
+  /*
+   * Add the composite overlay window to the cache, as this can be a reasonable
+   * Xdnd proxy as well.
+   * This is only done when the screen is composited in order to avoid mapping
+   * the COW. We assume that the CM is using the COW (which is true for pretty
+   * much any CM currently in use).
+   */
+  if (gdk_screen_is_composited (screen))
+    {
+      cow = XCompositeGetOverlayWindow (xdisplay, GDK_WINDOW_XWINDOW (root_window));
+      gdk_window_cache_add (result, cow, 0, 0, gdk_screen_get_width (screen), gdk_screen_get_height (screen), TRUE);
+      XCompositeReleaseOverlayWindow (xdisplay, GDK_WINDOW_XWINDOW (root_window));
+    }
+
   return result;
 }