Make middle-clicking on GTK tabs not count for closing if you release off of ...

chrome/browser/gtk/tabs/tab_gtk.cc

 // Copyright (c) 2006-2008 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.
 
 #include "chrome/browser/gtk/tabs/tab_gtk.h"
 
 #include "app/gfx/path.h"
 #include "app/l10n_util.h"
 #include "app/resource_bundle.h"
 #include "chrome/browser/gtk/gtk_dnd_util.h"
@@ skipping 157 matching lines @@
   } else if (event->button == 3) {
     tab->ShowContextMenu();
   }
 
   return TRUE;
 }
 
 // static
 gboolean TabGtk::OnMouseRelease(GtkWidget* widget, GdkEventButton* event,
                                 TabGtk* tab) {
-  if (event->button == 2) {
+  // Middle mouse up means close the tab, but only if the mouse is over it
+  // (like a button).
+  if (event->button == 2 &&
+      event->x >= 0 && event->y >= 0 &&
+      event->x < widget->allocation.width &&
+      event->y < widget.allocation.height) {
     tab->delegate_->CloseTab(tab);
   }
 
   return TRUE;
 }
 
 // static
 gboolean TabGtk::OnEnterNotify(GtkWidget* widget, GdkEventCrossing* event,
                                TabGtk* tab) {
   tab->OnMouseEntered();
@@ skipping 106 matching lines @@
   if (!menu_controller_.get())
     menu_controller_.reset(new ContextMenuController(this));
 
   menu_controller_->RunMenu();
 }
 
 void TabGtk::ContextMenuClosed() {
   delegate()->StopAllHighlighting();
   menu_controller_.reset();
 }