diff --git a/widget/src/windows/nsWindow.cpp b/widget/src/windows/nsWindow.cpp
index d98db26b40b2..3a557ea99c21 100644
--- a/widget/src/windows/nsWindow.cpp
+++ b/widget/src/windows/nsWindow.cpp
@@ -2108,6 +2108,63 @@ nsWindow::SetNonClientMargins(nsIntMargin &margins)
   return NS_OK;
 }
 
+void
+nsWindow::InvalidateNonClientRegion()
+{
+  // +-+-----------------------+-+
+  // | | app non-client chrome | |
+  // | +-----------------------+ |
+  // | |   app client chrome   | | }
+  // | +-----------------------+ | }
+  // | |      app content      | | } area we don't want to invalidate
+  // | +-----------------------+ | }
+  // | |   app client chrome   | | }
+  // | +-----------------------+ | 
+  // +---------------------------+ <
+  //  ^                         ^    windows non-client chrome
+  // client area = app *
+  RECT rect;
+  GetWindowRect(mWnd, &rect);
+  MapWindowPoints(NULL, mWnd, (LPPOINT)&rect, 2);
+  HRGN winRgn = CreateRectRgnIndirect(&rect);
+
+  // Subtract app client chrome and app content leaving
+  // windows non-client chrome and app non-client chrome
+  // in winRgn.
+  GetWindowRect(mWnd, &rect);
+  rect.top += mCaptionHeight;
+  rect.right -= mHorResizeMargin;
+  rect.bottom -= mHorResizeMargin;
+  rect.left += mVertResizeMargin;
+  MapWindowPoints(NULL, mWnd, (LPPOINT)&rect, 2);
+  HRGN clientRgn = CreateRectRgnIndirect(&rect);
+  CombineRgn(winRgn, winRgn, clientRgn, RGN_DIFF);
+  DeleteObject(clientRgn);
+
+  // triggers ncpaint and paint events for the two areas
+  RedrawWindow(mWnd, NULL, winRgn, RDW_FRAME|RDW_INVALIDATE);
+  DeleteObject(winRgn);
+}
+
+HRGN
+nsWindow::ExcludeNonClientFromPaintRegion(HRGN aRegion)
+{
+  RECT rect;
+  HRGN rgn = NULL;
+  if (aRegion == (HRGN)1) { // undocumented value indicating a full refresh
+    GetWindowRect(mWnd, &rect);
+    rgn = CreateRectRgnIndirect(&rect);
+  } else {
+    rgn = aRegion;
+  }
+  GetClientRect(mWnd, &rect);
+  MapWindowPoints(mWnd, NULL, (LPPOINT)&rect, 2);
+  HRGN nonClientRgn = CreateRectRgnIndirect(&rect);
+  CombineRgn(rgn, rgn, nonClientRgn, RGN_DIFF);
+  DeleteObject(nonClientRgn);
+  return rgn;
+}
+
 /**************************************************************
  *
  * SECTION: nsIWidget::SetBackgroundColor
@@ -4705,6 +4762,87 @@ PRBool nsWindow::ProcessMessage(UINT msg, WPARAM &wParam, LPARAM &lParam,
       break;
     }
 
+    case WM_SETTEXT:
+      /*
+       * WM_SETTEXT paints the titlebar area. Avoid this if we have a
+       * custom titlebar we paint ourselves.
+       */
+
+      if (mNonClientMargins.top == -1)
+        break;
+
+      {
+        // From msdn, the way around this is to disable the visible state
+        // temporarily. We need the text to be set but we don't want the
+        // redraw to occur.
+        DWORD style = GetWindowLong(mWnd, GWL_STYLE);
+        SetWindowLong(mWnd, GWL_STYLE, style & ~WS_VISIBLE);
+        *aRetValue = CallWindowProcW(GetPrevWindowProc(), mWnd,
+                                     msg, wParam, lParam);
+        SetWindowLong(mWnd, GWL_STYLE, style);
+        return PR_TRUE;
+      }
+
+    case WM_NCACTIVATE:
+    {
+      /*
+       * WM_NCACTIVATE paints nc areas. Avoid this and re-route painting
+       * through WM_NCPAINT via InvalidateNonClientRegion.
+       */
+
+      if (!mCustomNonClient)
+        break;
+
+#if MOZ_WINSDK_TARGETVER >= MOZ_NTDDI_LONGHORN
+      // let the dwm handle nc painting on glass
+      if(nsUXThemeData::CheckForCompositor())
+        break;
+#endif
+
+      if (wParam == TRUE) {
+        // going active
+        *aRetValue = FALSE; // ignored
+        result = PR_TRUE;
+        // invalidate to trigger a paint
+        InvalidateNonClientRegion();
+        break;
+      } else {
+        // going inactive
+        *aRetValue = TRUE; // go ahead and deactive
+        result = PR_TRUE;
+        // invalidate to trigger a paint
+        InvalidateNonClientRegion();
+        break;
+      }
+    }
+
+    case WM_NCPAINT:
+    {
+      /*
+       * Reset the non-client paint region so that it excludes the
+       * non-client areas we paint manually. Then call defwndproc
+       * to do the actual painting.
+       */
+
+      if (!mCustomNonClient)
+        break;
+
+#if MOZ_WINSDK_TARGETVER >= MOZ_NTDDI_LONGHORN
+      // let the dwm handle nc painting on glass
+      if(nsUXThemeData::CheckForCompositor())
+        break;
+#endif
+
+      HRGN paintRgn = ExcludeNonClientFromPaintRegion((HRGN)wParam);
+      LRESULT res = CallWindowProcW(GetPrevWindowProc(), mWnd,
+                                    msg, (WPARAM)paintRgn, lParam);
+      if (paintRgn != (HRGN)wParam)
+        DeleteObject(paintRgn);
+      *aRetValue = res;
+      result = PR_TRUE;
+    }
+    break;
+
 #ifndef WINCE
     case WM_POWERBROADCAST:
       // only hidden window handle this
diff --git a/widget/src/windows/nsWindow.h b/widget/src/windows/nsWindow.h
index 9b4cd79dad32..0599b52d9f20 100644
--- a/widget/src/windows/nsWindow.h
+++ b/widget/src/windows/nsWindow.h
@@ -302,6 +302,8 @@ protected:
   PRBool                  CanTakeFocus();
   PRBool                  UpdateNonClientMargins(PRInt32 aSizeMode = -1, PRBool aReflowWindow = PR_TRUE);
   void                    ResetLayout();
+  void                    InvalidateNonClientRegion();
+  HRGN                    ExcludeNonClientFromPaintRegion(HRGN aRegion);
 #if !defined(WINCE)
   static void             InitTrackPointHack();
 #endif