From 82e84361523b736adc26b8810e6704a127cc0b5c Mon Sep 17 00:00:00 2001
From: "kipp%netscape.com" <kipp%netscape.com>
Date: Fri, 30 Oct 1998 22:05:22 +0000
Subject: [PATCH] Fixed a coordinate system bug with Offset method

---
 layout/base/src/nsSpaceManager.cpp | 7 ++++++-
 layout/generic/nsSpaceManager.cpp  | 7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/layout/base/src/nsSpaceManager.cpp b/layout/base/src/nsSpaceManager.cpp
index 0ef29a7a04f..04edb3927bb 100644
--- a/layout/base/src/nsSpaceManager.cpp
+++ b/layout/base/src/nsSpaceManager.cpp
@@ -752,8 +752,13 @@ PRBool nsSpaceManager::OffsetRegion(nsIFrame* aFrame, nscoord aDx, nscoord aDy)
     return PR_FALSE;
   }
 
+  // Compute new rect for the region; note that we have to translate
+  // from the global coordinate system (frameInfo->rect) to our
+  // current local coordinate system before adding the rect region
+  // again (since AddRectRegion operates relative to the current
+  // translation).
   nsRect  rect(frameInfo->rect);
-  rect.MoveBy(aDx, aDy);
+  rect.MoveBy(-mX + aDx, -mY + aDy);
 
   // Verify that the offset is within the defined coordinate space
   if ((rect.x < 0) || (rect.y < 0)) {
diff --git a/layout/generic/nsSpaceManager.cpp b/layout/generic/nsSpaceManager.cpp
index 0ef29a7a04f..04edb3927bb 100644
--- a/layout/generic/nsSpaceManager.cpp
+++ b/layout/generic/nsSpaceManager.cpp
@@ -752,8 +752,13 @@ PRBool nsSpaceManager::OffsetRegion(nsIFrame* aFrame, nscoord aDx, nscoord aDy)
     return PR_FALSE;
   }
 
+  // Compute new rect for the region; note that we have to translate
+  // from the global coordinate system (frameInfo->rect) to our
+  // current local coordinate system before adding the rect region
+  // again (since AddRectRegion operates relative to the current
+  // translation).
   nsRect  rect(frameInfo->rect);
-  rect.MoveBy(aDx, aDy);
+  rect.MoveBy(-mX + aDx, -mY + aDy);
 
   // Verify that the offset is within the defined coordinate space
   if ((rect.x < 0) || (rect.y < 0)) {