From c29e28bbd056ff79b917e0085872ada68919519c Mon Sep 17 00:00:00 2001
From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 23 Apr 2010 14:41:37 +1200
Subject: [PATCH] Bug 548792. Fix rect coordinate adjustment. r=mats

---
 layout/base/nsPresShell.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 006e0fd0223a..f77c78b6ff14 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -4101,7 +4101,9 @@ PresShell::ScrollFrameRectIntoView(nsIFrame*     aFrame,
       ScrollToShowRect(sf, rect - sf->GetScrolledFrame()->GetPosition(),
                        aVPercent, aHPercent, aFlags);
       nsPoint newPosition = sf->GetScrollPosition();
-      rect += newPosition - oldPosition;
+      // If the scroll position increased, that means our content moved up,
+      // so our rect's offset should decrease
+      rect += oldPosition - newPosition;
 
       if (oldPosition != newPosition) {
         didScroll = PR_TRUE;