[gtk+] gdkwindow: subsurface in gdk_window_get_parent()

[Olivier Fourdan <ofourdan src gnome org>]

commit 19ce6a8bc5a13cef322932ea302164127f355865
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Wed Feb 1 15:09:52 2017 +0100

    gdkwindow: subsurface in gdk_window_get_parent()
    
    When the GtkWidget hierarchy does not match the GdkWindow hierarchy, the
    GtkWidget code may find a common ancestor that cannot be found while
    traversing the GdkWindow tree using gdk_window_get_parent().
    
    This happens with for example on Wayland, a GtkPopover has another
    GtkPopover as parent, in this case, the GdkWindow parent is the root
    window, whereas the GtkWidget parent is the other GtkPopover.
    
    That confuses the gtk_widget_translate_coordinates() logic which will
    bail out in this case and won't return the translated coordinates.
    
    Make gdk_window_get_effective_parent() aware of subsurfaces and use the
    transient_for which represents the actual parent (whereas the parent
    might be pointing to the root window).
    
    Bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=774148

 gdk/gdkwindow.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)
---
diff --git a/gdk/gdkwindow.c b/gdk/gdkwindow.c
index fe14493..59d21d4 100644
--- a/gdk/gdkwindow.c
+++ b/gdk/gdkwindow.c
@@ -456,6 +456,12 @@ gdk_window_get_property (GObject    *object,
     }
 }
 
+static gboolean
+gdk_window_is_subsurface (GdkWindow *window)
+{
+   return window->window_type == GDK_WINDOW_SUBSURFACE;
+}
+
 static GdkWindow *
 gdk_window_get_impl_window (GdkWindow *window)
 {
@@ -1729,7 +1735,10 @@ gdk_window_get_parent (GdkWindow *window)
 {
   g_return_val_if_fail (GDK_IS_WINDOW (window), NULL);
 
-  return window->parent;
+  if (gdk_window_is_subsurface (window))
+    return window->transient_for;
+  else
+    return window->parent;
 }
 
 /**