[gtk+] fix race between fetching owner of composit selection, and

[Michael Meeks <michael src gnome org>]

commit db88f084bc83dff85b3c4c6c62a294e8e1c595de
Author: Michael Meeks <michael meeks novell com>
Date:   Mon Sep 14 14:27:42 2009 +0100

    fix race between fetching owner of composit selection, and
    registering as a listener for changes; bug#594913

 gdk/x11/gdkdisplay-x11.c |    3 +--
 gdk/x11/gdkscreen-x11.c  |   18 ++++++++++++++++--
 gdk/x11/gdkscreen-x11.h  |    1 +
 3 files changed, 18 insertions(+), 4 deletions(-)
---
diff --git a/gdk/x11/gdkdisplay-x11.c b/gdk/x11/gdkdisplay-x11.c
index a384b15..2b10a93 100644
--- a/gdk/x11/gdkdisplay-x11.c
+++ b/gdk/x11/gdkdisplay-x11.c
@@ -402,8 +402,7 @@ gdk_display_open (const gchar *display_name)
   _gdk_dnd_init (display);
 
   for (i = 0; i < ScreenCount (display_x11->xdisplay); i++)
-    gdk_display_request_selection_notification (display, 
-						GDK_SCREEN_X11 (display_x11->screens[i])->cm_selection_atom);
+    _gdk_x11_screen_setup (display_x11->screens[i]);
 
   g_signal_emit_by_name (gdk_display_manager_get(),
 			 "display_opened", display);
diff --git a/gdk/x11/gdkscreen-x11.c b/gdk/x11/gdkscreen-x11.c
index a668aeb..93d6e4a 100644
--- a/gdk/x11/gdkscreen-x11.c
+++ b/gdk/x11/gdkscreen-x11.c
@@ -989,8 +989,6 @@ _gdk_x11_screen_new (GdkDisplay *display,
   screen_x11->wmspec_check_window = None;
   /* we want this to be always non-null */
   screen_x11->window_manager_name = g_strdup ("unknown");
-  screen_x11->cm_selection_atom = make_cm_atom (screen_number);
-  screen_x11->is_composited = check_is_composited (display, screen_x11);
   
   init_multihead (screen);
   init_randr_support (screen);
@@ -1001,6 +999,22 @@ _gdk_x11_screen_new (GdkDisplay *display,
   return screen;
 }
 
+/*
+ * It is important that we first request the selection
+ * notification, and then setup the initial state of
+ * is_composited to avoid a race condition here.
+ */
+void
+_gdk_x11_screen_setup (GdkScreen *screen)
+{
+  GdkScreenX11 *screen_x11 = GDK_SCREEN_X11 (screen);
+
+  screen_x11->cm_selection_atom = make_cm_atom (screen_x11->screen_num);
+  gdk_display_request_selection_notification (screen_x11->display, 
+					      screen_x11->cm_selection_atom);
+  screen_x11->is_composited = check_is_composited (screen_x11->display, screen_x11);
+}
+
 /**
  * gdk_screen_is_composited:
  * @screen: a #GdkScreen
diff --git a/gdk/x11/gdkscreen-x11.h b/gdk/x11/gdkscreen-x11.h
index 8a743f5..0d1548c 100644
--- a/gdk/x11/gdkscreen-x11.h
+++ b/gdk/x11/gdkscreen-x11.h
@@ -122,6 +122,7 @@ GType       _gdk_screen_x11_get_type (void);
 GdkScreen * _gdk_x11_screen_new      (GdkDisplay *display,
 				      gint	  screen_number);
 
+void _gdk_x11_screen_setup                  (GdkScreen *screen);
 void _gdk_x11_screen_window_manager_changed (GdkScreen *screen);
 void _gdk_x11_screen_size_changed           (GdkScreen *screen,
 					     XEvent    *event);