Have panels respond to changes in work area on Linux.

ui/base/x/root_window_property_watcher_x.h

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_BASE_X_ROOT_WINDOW_PROPERTY_WATCHER_X_H_
+#define UI_BASE_X_ROOT_WINDOW_PROPERTY_WATCHER_X_H_
+#pragma once
+
+#include <gdk/gdk.h>
+
+#include "base/memory/singleton.h"
+#include "ui/base/gtk/gtk_signal.h"
+#include "ui/base/ui_export.h"
+
+namespace ui {

[sky, 2011/11/18 17:54:22]

Put this in an internal namespace (ui::internal) if it's not to be used
externally. Also, you shouldn't need need UI_EXPORT if the class is only used in
ui.

[prasadt, 2011/11/18 22:31:42]

Done.

+
+// This class keeps track of changes to properties on root window. This is not

[sky, 2011/11/18 17:54:22]

'on root' -> 'on the root'

[prasadt, 2011/11/18 22:31:42]

Done.

+// to be used directly. Implement a watcher for the specific property you're
+// interested in.
+class UI_EXPORT RootWindowPropertyWatcherX {
+ public:
+  static RootWindowPropertyWatcherX* GetInstance();
+
+ private:
+  friend struct DefaultSingletonTraits<RootWindowPropertyWatcherX>;
+
+  RootWindowPropertyWatcherX();
+  ~RootWindowPropertyWatcherX();
+
+  // Callback for PropertyChange XEvents.
+  CHROMEG_CALLBACK_1(RootWindowPropertyWatcherX, GdkFilterReturn,
+                     OnWindowXEvent, GdkXEvent*, GdkEvent*);
+
+  DISALLOW_COPY_AND_ASSIGN(RootWindowPropertyWatcherX);
+};
+
+}  // namespace ui
+
+#endif  // UI_BASE_X_ROOT_WINDOW_PROPERTY_WATCHER_X_H_