[gtk+] Only select for button and pointer event on toplevels

[Alexander Larsson <alexl src gnome org>]

commit 6fef640debbe468586ff866cbef38d7a29c452d1
Author: Alexander Larsson <alexl redhat com>
Date:   Tue Sep 29 12:56:57 2009 +0200

    Only select for button and pointer event on toplevels
    
    These event types propagate up the hierarchy anyway, so this means
    we avoid setting it unnecessarily. This is especially important
    for button press event, since only one client can select for this
    on each window, causing X errors if two clients do it.

 gdk/gdkwindow.c |   53 ++++++++++++++++++++++++++++++++++++-----------------
 1 files changed, 36 insertions(+), 17 deletions(-)
---
diff --git a/gdk/gdkwindow.c b/gdk/gdkwindow.c
index 4130b52..d4ce492 100644
--- a/gdk/gdkwindow.c
+++ b/gdk/gdkwindow.c
@@ -1163,25 +1163,44 @@ get_native_event_mask (GdkWindowObject *private)
     return private->event_mask;
   else
     {
-      return
-	/* We need thse for all native window so we can emulate
-	   events on children: */
+      GdkEventMask mask;
+
+      /* Do whatever the app asks to, since the app
+       * may be asking for weird things for native windows,
+       * but filter out things that override the special
+       * requests below. */
+      mask = private->event_mask &
+	~(GDK_POINTER_MOTION_HINT_MASK |
+	  GDK_BUTTON_MOTION_MASK |
+	  GDK_BUTTON1_MOTION_MASK |
+	  GDK_BUTTON2_MOTION_MASK |
+	  GDK_BUTTON3_MOTION_MASK);
+
+      /* We need thse for all native windows so we can
+	 emulate events on children: */
+      mask |=
 	GDK_EXPOSURE_MASK |
 	GDK_VISIBILITY_NOTIFY_MASK |
-	GDK_POINTER_MOTION_MASK |
-	GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK |
-	GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK |
-	GDK_SCROLL_MASK |
-	/* Then do whatever the app asks to, since the app
-	 * may be asking for weird things for native windows,
-	 * but filter out things that override the above
-	 * requests somehow. */
-	(private->event_mask &
-	 ~(GDK_POINTER_MOTION_HINT_MASK |
-	   GDK_BUTTON_MOTION_MASK |
-	   GDK_BUTTON1_MOTION_MASK |
-	   GDK_BUTTON2_MOTION_MASK |
-	   GDK_BUTTON3_MOTION_MASK));
+	GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK;
+
+      /* Additionally we select for pointer and button events
+       * for toplevels as we need to get these to emulate
+       * them for non-native subwindows. Even though we don't
+       * select on them for all native windows we will get them
+       * as the events are propagated out to the first window
+       * that select for them.
+       * Not selecting for button press on all windows is an
+       * important thing, because in X only one client can do
+       * so, and we don't want to unexpectedly prevent another
+       * client from doing it.
+       */
+      if (gdk_window_is_toplevel (private))
+	mask |=
+	  GDK_POINTER_MOTION_MASK |
+	  GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK |
+	  GDK_SCROLL_MASK;
+
+      return mask;
     }
 }