[gtk+/client-side-windows: 107/284] Don't expose a temporary grab during a scrollwheel button press/release cycle.

[Alexander Larsson <alexl src gnome org>]

commit 8a0ef57ba31b16a07ae2bfea99985a3ae9dc1800
Author: Alexander Larsson <alexl redhat com>
Date:   Wed Jan 21 14:42:46 2009 +0100

    Don't expose a temporary grab during a scrollwheel button press/release cycle.
    
    If we do this there is a short window where we think there is a grab, and
    if we generate a client side pointer motion event in this time (e.g. from
    a window move) we could be delivering that according to the grab. But in
    the Xserver that grab is infinitely short as it sends Press and then
    Release immediately.
    
    To see a problem from this, try using the scrollwheel to quickly scroll
    in the testgtk list of buttons.
---
 gdk/x11/gdkevents-x11.c |   19 ++++++++++++-------
 1 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/gdk/x11/gdkevents-x11.c b/gdk/x11/gdkevents-x11.c
index 4f02dc2..5167212 100644
--- a/gdk/x11/gdkevents-x11.c
+++ b/gdk/x11/gdkevents-x11.c
@@ -1213,7 +1213,15 @@ gdk_event_translate (GdkDisplay *display,
 
       set_user_time (window, event);
 
-      _gdk_xgrab_check_button_event (window, xevent);
+      /* We treat button presses as scroll wheel events, so don't expose
+       * this grab to gtk, as it will be immediately released. If we do
+       * expose it there is a short time before we receive the Release
+       * where a client-side generated pointer motion event could be handled
+       * as if the grab was effect.
+       */
+      if (!(xevent->xbutton.button == 4 || xevent->xbutton.button == 5 ||
+	    xevent->xbutton.button == 6 || xevent->xbutton.button == 7))
+	_gdk_xgrab_check_button_event (window, xevent);
       break;
       
     case ButtonRelease:
@@ -1236,7 +1244,7 @@ gdk_event_translate (GdkDisplay *display,
           xevent->xbutton.button == 6 || xevent->xbutton.button ==7)
 	{
 	  return_val = FALSE;
-	  goto release_out;
+	  break;
 	}
 
       event->button.type = GDK_BUTTON_RELEASE;
@@ -1252,13 +1260,10 @@ gdk_event_translate (GdkDisplay *display,
       event->button.device = display->core_pointer;
 
       if (!set_screen_from_root (display, event, xevent->xbutton.root))
-	{
-	  return_val = FALSE;
-	  goto release_out;
-	}
+	return_val = FALSE;
       
-    release_out:
       _gdk_xgrab_check_button_event (window, xevent);
+      
       break;
       
     case MotionNotify: