From ba88babee3ac0ebd7e8739b2d87e5844024f71d6 Mon Sep 17 00:00:00 2001
From: Bas Schouten <bschouten@mozilla.com>
Date: Wed, 1 Dec 2010 04:20:05 +0100
Subject: [PATCH] Bug 615462: Only draw native theme for the dirty rect. r=roc
 a=blocking-final

---
 layout/base/nsCSSRendering.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/layout/base/nsCSSRendering.cpp b/layout/base/nsCSSRendering.cpp
index 3b437d485c0..8c43912e2d9 100644
--- a/layout/base/nsCSSRendering.cpp
+++ b/layout/base/nsCSSRendering.cpp
@@ -1213,8 +1213,12 @@ nsCSSRendering::PaintBoxShadowOuter(nsPresContext* aPresContext,
       devCtx->CreateRenderingContextInstance(*getter_AddRefs(wrapperCtx));
       wrapperCtx->Init(devCtx, shadowContext);
       wrapperCtx->Translate(shadowItem->mXOffset, shadowItem->mYOffset);
+
+      nsRect nativeRect;
+      nativeRect.IntersectRect(frameRect, aDirtyRect);
+
       aPresContext->GetTheme()->DrawWidgetBackground(wrapperCtx, aForFrame,
-          styleDisplay->mAppearance, aFrameArea, frameRect);
+          styleDisplay->mAppearance, aFrameArea, nativeRect);
     } else {
       // Clip out the area of the actual frame so the shadow is not shown within
       // the frame