Index: ntuser/painting.c
===================================================================
--- ntuser/painting.c	(revision 19665)
+++ ntuser/painting.c	(working copy)
@@ -81,11 +81,14 @@
    return TRUE;
 }
 
-VOID FASTCALL
-IntValidateParent(PWINDOW_OBJECT Child, HRGN ValidRegion)
+BOOL FASTCALL
+IntValidateParent(PWINDOW_OBJECT Child, HRGN ValidRegion, BOOL Recurse)
 {
    PWINDOW_OBJECT ParentWindow = Child->Parent;
 
+   while (ParentWindow && ParentWindow->Style & WS_CHILD)
+      ParentWindow = ParentWindow->Parent;
+
    while (ParentWindow)
    {
       if (ParentWindow->Style & WS_CLIPCHILDREN)
@@ -93,13 +96,17 @@
 
       if (ParentWindow->UpdateRegion != 0)
       {
-         NtGdiCombineRgn(ParentWindow->UpdateRegion, ParentWindow->UpdateRegion,
-            ValidRegion, RGN_DIFF);
-         /* FIXME: If the resulting region is empty, remove fake posted paint message */
+         if (Recurse)
+            return FALSE;
+
+         IntInvalidateWindows(ParentWindow, Child->UpdateRegion,
+                              RDW_VALIDATE | RDW_NOCHILDREN);
       }
 
       ParentWindow = ParentWindow->Parent;
    }
+
+   return TRUE;
 }
 
 /**
@@ -219,7 +226,7 @@
  */
 
 STATIC VOID FASTCALL
-co_IntPaintWindows(PWINDOW_OBJECT Window, ULONG Flags)
+co_IntPaintWindows(PWINDOW_OBJECT Window, ULONG Flags, BOOL Recurse)
 {
    HDC hDC;
    HWND hWnd = Window->hSelf;
@@ -229,7 +236,8 @@
    {
       if (Window->UpdateRegion)
       {
-         IntValidateParent(Window, Window->UpdateRegion);
+         if (!IntValidateParent(Window, Window->UpdateRegion, Recurse))
+            return;
       }
 
       if (Flags & RDW_UPDATENOW)
@@ -290,6 +298,7 @@
 
       if ((List = IntWinListChildren(Window)))
       {
+         /* FIXME: Handle WS_EX_TRANSPARENT */
          for (phWnd = List; *phWnd; ++phWnd)
          {
             Window = UserGetWindowObject(*phWnd);
@@ -297,7 +306,7 @@
             {
                USER_REFERENCE_ENTRY Ref;
                UserRefObjectCo(Window, &Ref);
-               co_IntPaintWindows(Window, Flags);
+               co_IntPaintWindows(Window, Flags, TRUE);
                UserDerefObjectCo(Window);
             }
          }
@@ -565,7 +574,7 @@
 
    if (Flags & (RDW_ERASENOW | RDW_UPDATENOW))
    {
-      co_IntPaintWindows(Window, Flags);
+      co_IntPaintWindows(Window, Flags, FALSE);
    }
 
    /*
Index: ntuser/winpos.c
===================================================================
--- ntuser/winpos.c	(revision 19665)
+++ ntuser/winpos.c	(working copy)
@@ -1194,7 +1194,6 @@
                         CopyRect.left + (OldWindowRect.left - NewWindowRect.left),
                         CopyRect.top + (OldWindowRect.top - NewWindowRect.top), SRCCOPY);
             UserReleaseDC(Window, Dc, FALSE);
-            IntValidateParent(Window, CopyRgn);
             NtGdiOffsetRgn(CopyRgn, -NewWindowRect.left, -NewWindowRect.top);
          }
          else if(VisRgn)
Index: include/painting.h
===================================================================
--- include/painting.h	(revision 19665)
+++ include/painting.h	(working copy)
@@ -5,10 +5,10 @@
 #include <include/msgqueue.h>
 #include <include/window.h>
 
-VOID FASTCALL
-IntValidateParent(PWINDOW_OBJECT Child, HRGN ValidRegion);
 BOOL FASTCALL
 co_UserRedrawWindow(PWINDOW_OBJECT Wnd, const RECT* UpdateRect, HRGN UpdateRgn, ULONG Flags);
+VOID FASTCALL
+IntInvalidateWindows(PWINDOW_OBJECT Window, HRGN hRgn, ULONG Flags);
 BOOL FASTCALL
 IntGetPaintMessage(HWND hWnd, UINT MsgFilterMin, UINT MsgFilterMax, PW32THREAD Thread,
                    MSG *Message, BOOL Remove);