Scroll-wheeling, whilst over the tab-strip, now switches tabs on GTK/Linux.

chrome/browser/gtk/browser_titlebar.h

 // Copyright (c) 2009 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.
 //
 // A helper class that contains the gtk widgets that make up the titlebar.  The
 // titlebar consists of the tabstrip and if the custom chrome frame is turned
 // on, it includes the taller titlebar and minimize, restore, maximize, and
 // close buttons.
 
 #ifndef CHROME_BROWSER_GTK_BROWSER_TITLEBAR_H_
@@ skipping 41 matching lines @@
 
   // Update the titlebar spacing based on the custom frame and maximized state.
   void UpdateTitlebarAlignment();
 
   // Callback for changes to window state.  This includes
   // maximizing/restoring/minimizing the window.
   static gboolean OnWindowStateChanged(GtkWindow* window,
                                        GdkEventWindowState* event,
                                        BrowserTitlebar* titlebar);
 
+  // Callback for mousewheel events.
+  static gboolean OnScroll(GtkWidget* widget, GdkEventScroll* event,
+                           BrowserTitlebar* titlebar);
+
   // Callback for min/max/close buttons.
   static void OnButtonClicked(GtkWidget* button, BrowserTitlebar* window);
 
   // -- Context Menu -----------------------------------------------------------
 
   // MenuGtk::Delegate implementation:
   virtual bool IsCommandEnabled(int command_id) const;
   virtual bool IsItemChecked(int command_id) const;
   virtual void ExecuteCommand(int command_id);
 
@@ skipping 23 matching lines @@
   scoped_ptr<CustomDrawButton> minimize_button_;
   scoped_ptr<CustomDrawButton> maximize_button_;
   scoped_ptr<CustomDrawButton> restore_button_;
   scoped_ptr<CustomDrawButton> close_button_;
 
   // The context menu.
   scoped_ptr<MenuGtk> context_menu_;
 };
 
 #endif  // CHROME_BROWSER_GTK_BROWSER_TITLEBAR_H_