[gtk+] Fix window button updates in split headers

[Matthias Clasen <matthiasc src gnome org>]

commit c8d6231c3c55dc9f357a2436cbc89bef23163d57
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Apr 14 17:05:34 2015 -0400

    Fix window button updates in split headers
    
    We were only updating window buttons when the headerbar was
    a direct child of the window. That is not the case in more
    complicated situations, such as the split headers in gedit
    or polari. To fix such cases, make the headerbar itself listen
    for state changes on its toplevel.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=747805

 gtk/gtkheaderbar.c |   31 +++++++++++++++++++++++++++++++
 1 files changed, 31 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkheaderbar.c b/gtk/gtkheaderbar.c
index f2f2878..bf95295 100644
--- a/gtk/gtkheaderbar.c
+++ b/gtk/gtkheaderbar.c
@@ -1812,6 +1812,36 @@ gtk_header_bar_unrealize (GtkWidget *widget)
   GTK_WIDGET_CLASS (gtk_header_bar_parent_class)->unrealize (widget);
 }
 
+static gboolean
+window_state_changed (GtkWidget           *window,
+                      GdkEventWindowState *event,
+                      gpointer             data)
+{
+  GtkHeaderBar *bar = GTK_HEADER_BAR (data);
+
+  if (event->changed_mask & (GDK_WINDOW_STATE_FULLSCREEN | GDK_WINDOW_STATE_MAXIMIZED | 
GDK_WINDOW_STATE_TILED))
+    _gtk_header_bar_update_window_buttons (bar);
+
+  return FALSE;
+}
+
+static void
+gtk_header_bar_hierarchy_changed (GtkWidget *widget,
+                                  GtkWidget *previous_toplevel)
+{
+  GtkWidget *toplevel;
+
+  toplevel = gtk_widget_get_toplevel (widget);
+
+  if (previous_toplevel)
+    g_signal_handlers_disconnect_by_func (previous_toplevel,
+                                          window_state_changed, widget);
+
+  if (toplevel)
+    g_signal_connect_after (toplevel, "window-state-event",
+                            G_CALLBACK (window_state_changed), widget);
+}
+
 static void
 gtk_header_bar_class_init (GtkHeaderBarClass *class)
 {
@@ -1831,6 +1861,7 @@ gtk_header_bar_class_init (GtkHeaderBarClass *class)
   widget_class->draw = gtk_header_bar_draw;
   widget_class->realize = gtk_header_bar_realize;
   widget_class->unrealize = gtk_header_bar_unrealize;
+  widget_class->hierarchy_changed = gtk_header_bar_hierarchy_changed;
 
   container_class->add = gtk_header_bar_add;
   container_class->remove = gtk_header_bar_remove;