a11y: restore window:activate/deactivate emission

1b9aa1b708 ('a11y: drop the focus tracker') removed a bit too much.  We
still have to emit window:activate/deactivate events.  They are easy to
emit anyway.

Fixes #127

gtk/a11y/gtkaccessibility.h

@@ -23,10 +23,13 @@
 
 G_BEGIN_DECLS
 
-void      _gtk_accessibility_init        (void);
+void      _gtk_accessibility_init              (void);
 
-gboolean  _gtk_accessibility_key_snooper (GtkWidget   *widget,
-                                          GdkEventKey *event);
+gboolean  _gtk_accessibility_key_snooper       (GtkWidget   *widget,
+                                                GdkEventKey *event);
+
+void      _gtk_window_accessible_set_is_active (GtkWindow   *window,
+                                                gboolean     is_active);
 
 G_END_DECLS
 

gtk/a11y/gtkwindowaccessible.c

@@ -20,9 +20,11 @@
 
 #include <gtk/gtk.h>
 
+#include "gtkaccessibility.h"
 #include "gtkwidgetaccessibleprivate.h"
 #include "gtkwindowaccessible.h"
 #include "gtktoplevelaccessible.h"
+#include "gtkwidgetprivate.h"
 #include "gtkwindowprivate.h"
 
 /* atkcomponent.h */
@@ -442,6 +444,19 @@ gtk_window_accessible_get_size (AtkComponent *component,
   *height = rect.height;
 }
 
+void
+_gtk_window_accessible_set_is_active (GtkWindow   *window,
+                                      gboolean     is_active)
+{
+  AtkObject *accessible = _gtk_widget_peek_accessible (GTK_WIDGET (window));
+
+  if (accessible == NULL)
+    return;
+
+  g_signal_emit_by_name (accessible, is_active ? "activate" : "deactivate");
+}
+
+
 static void
 atk_component_interface_init (AtkComponentIface *iface)
 {

gtk/gtkwindow.c

@@ -10472,6 +10472,7 @@ _gtk_window_set_is_active (GtkWindow *window,
         }
 
       g_object_notify_by_pspec (G_OBJECT (window), window_props[PROP_IS_ACTIVE]);
+      _gtk_window_accessible_set_is_active (window, is_active);
     }
 }