Makes tree double duffered so that it doesn't flicker during resize....

chrome/views/tree_view.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/views/tree_view.h"
 
 #include <shellapi.h>
 
 #include "base/win_util.h"
 #include "chrome/app/theme/theme_resources.h"
@@ skipping 581 matching lines @@
 
 LRESULT CALLBACK TreeView::TreeWndProc(HWND window,
                                        UINT message,
                                        WPARAM w_param,
                                        LPARAM l_param) {
   TreeViewWrapper* wrapper = reinterpret_cast<TreeViewWrapper*>(
       GetWindowLongPtr(window, GWLP_USERDATA));
   DCHECK(wrapper);
   TreeView* tree = wrapper->tree_view;
   switch (message) {
+    case WM_ERASEBKGND:
+      return 1;
+
+    case WM_PAINT: {
+      ChromeCanvasPaint canvas(window);
+      if (canvas.isEmpty())
+        return 0;
+
+      SendMessage(window, WM_PRINTCLIENT,
+                  reinterpret_cast<WPARAM>(canvas.beginPlatformPaint()), 0);
+      canvas.endPlatformPaint();
+      return 0;
+    }
+
     case WM_RBUTTONDOWN:
       if (tree->select_on_right_mouse_down_) {
         TVHITTESTINFO hit_info;
         hit_info.pt.x = GET_X_LPARAM(l_param);
         hit_info.pt.y = GET_Y_LPARAM(l_param);
         HTREEITEM hit_item = TreeView_HitTest(window, &hit_info);
         if (hit_item && (hit_info.flags & (TVHT_ONITEM | TVHT_ONITEMRIGHT |
                                            TVHT_ONITEMINDENT)) != 0)
           TreeView_SelectItem(tree->tree_view_, hit_item);
       }
       // Fall through and let the default handler process as well.
       break;
   }
   WNDPROC handler = tree->original_handler_;
   DCHECK(handler);
   return CallWindowProc(handler, window, message, w_param, l_param);
 }
 
 }  // namespace views