diff --git a/widget/src/windows/nsWindow.cpp b/widget/src/windows/nsWindow.cpp
index 6ce98a058126..5f4551ec424b 100644
--- a/widget/src/windows/nsWindow.cpp
+++ b/widget/src/windows/nsWindow.cpp
@@ -1217,8 +1217,7 @@ void nsWindow::SetThemeRegion()
 
 /**************************************************************
  *
- * SECTION: nsIWidget::Move, nsIWidget::Resize,
- * nsIWidget::Size, nsIWidget::BeginResizeDrag
+ * SECTION: nsIWidget::Move, nsIWidget::Resize, nsIWidget::Size
  *
  * Repositioning and sizing a window.
  *
@@ -1342,63 +1341,6 @@ NS_METHOD nsWindow::Resize(PRInt32 aX, PRInt32 aY, PRInt32 aWidth, PRInt32 aHeig
   return NS_OK;
 }
 
-NS_IMETHODIMP
-nsWindow::BeginResizeDrag(nsGUIEvent* aEvent, PRInt32 aHorizontal, PRInt32 aVertical)
-{
-  NS_ENSURE_ARG_POINTER(aEvent);
-
-  if (aEvent->eventStructType != NS_MOUSE_EVENT) {
-    // you can only begin a resize drag with a mouse event
-    return NS_ERROR_INVALID_ARG;
-  }
-
-  nsMouseEvent* mouseEvent = static_cast<nsMouseEvent*>(aEvent);
-  if (mouseEvent->button != nsMouseEvent::eLeftButton) {
-    // you can only begin a resize drag with the left mouse button
-    return NS_ERROR_INVALID_ARG;
-  }
-
-  // work out what sizemode we're talking about
-  WPARAM syscommand;
-  if (aVertical < 0) {
-    if (aHorizontal < 0) {
-      syscommand = SC_SIZE | WMSZ_TOPLEFT;
-    } else if (aHorizontal == 0) {
-      syscommand = SC_SIZE | WMSZ_TOP;
-    } else {
-      syscommand = SC_SIZE | WMSZ_TOPRIGHT;
-    }
-  } else if (aVertical == 0) {
-    if (aHorizontal < 0) {
-      syscommand = SC_SIZE | WMSZ_LEFT;
-    } else if (aHorizontal == 0) {
-      return NS_ERROR_INVALID_ARG;
-    } else {
-      syscommand = SC_SIZE | WMSZ_RIGHT;
-    }
-  } else {
-    if (aHorizontal < 0) {
-      syscommand = SC_SIZE | WMSZ_BOTTOMLEFT;
-    } else if (aHorizontal == 0) {
-      syscommand = SC_SIZE | WMSZ_BOTTOM;
-    } else {
-      syscommand = SC_SIZE | WMSZ_BOTTOMRIGHT;
-    }
-  }
-
-  // resizing doesn't work if the mouse is already captured
-  CaptureMouse(PR_FALSE);
-
-  // find the top-level window
-  HWND toplevelWnd = GetTopLevelHWND(mWnd, PR_TRUE);
-
-  // tell Windows to start the resize
-  ::PostMessage(toplevelWnd, WM_SYSCOMMAND, syscommand,
-                POINTTOPOINTS(aEvent->refPoint));
-
-  return NS_OK;
-}
-
 /**************************************************************
  *
  * SECTION: Window Z-order and state.
diff --git a/widget/src/windows/nsWindow.h b/widget/src/windows/nsWindow.h
index 2ce5fa19848a..95b5ca8c45b6 100644
--- a/widget/src/windows/nsWindow.h
+++ b/widget/src/windows/nsWindow.h
@@ -150,7 +150,6 @@ public:
   NS_IMETHOD              GetAttention(PRInt32 aCycleCount);
   virtual PRBool          HasPendingInputEvent();
   gfxASurface             *GetThebesSurface();
-  NS_IMETHOD              BeginResizeDrag(nsGUIEvent* aEvent, PRInt32 aHorizontal, PRInt32 aVertical);
   NS_IMETHOD              OnDefaultButtonLoaded(const nsIntRect &aButtonRect);
   NS_IMETHOD              OverrideSystemMouseScrollSpeed(PRInt32 aOriginalDelta, PRBool aIsHorizontal, PRInt32 &aOverriddenDelta);