Converts BaseView to be non-opaque, which will fix drawing of...

chrome/browser/tab_contents/tab_contents_view_mac.mm

 // 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/tab_contents/tab_contents_view_mac.h"
 
 #include "chrome/browser/browser.h" // TODO(beng): this dependency is awful.
 #include "chrome/browser/cocoa/sad_tab_view.h"
 #include "chrome/browser/renderer_host/render_widget_host.h"
 #include "chrome/browser/renderer_host/render_widget_host_view_mac.h"
@@ skipping 243 matching lines @@
   if (TabContentsView_->tab_contents()->delegate()) {
     if ([theEvent type] == NSMouseMoved)
       TabContentsView_->tab_contents()->delegate()->
           ContentsMouseEvent(TabContentsView_->tab_contents(), true);
     if ([theEvent type] == NSMouseExited)
       TabContentsView_->tab_contents()->delegate()->
           ContentsMouseEvent(TabContentsView_->tab_contents(), false);
   }
 }
 
+- (BOOL)mouseDownCanMoveWindow {
+  // This is needed to prevent mouseDowns from moving the window
+  // around.  The default implementation returns YES only for opaque
+  // views.  TabContentsViewCocoa does not draw itself in any way, but
+  // its subviews do paint their entire frames.  Returning NO here
+  // saves us the effort of overriding this method in every possible
+  // subview.
+  return NO;
+}
+
 // In the Windows version, we always have cut/copy/paste enabled. This is sub-
 // optimal, but we do it too. TODO(avi): Plumb the "can*" methods up from
 // WebCore.
 
 - (void)cut:(id)sender {
   TabContentsView_->tab_contents()->Cut();
 }
 
 - (void)copy:(id)sender {
   TabContentsView_->tab_contents()->Copy();
 }
 
 - (void)paste:(id)sender {
   TabContentsView_->tab_contents()->Paste();
 }
 
 // Tons of stuff goes here, where we grab events going on in Cocoaland and send
 // them into the C++ system. TODO(avi): all that jazz
 
 @end