Index: include/ntuser.h
===================================================================
--- include/ntuser.h	(revision 73520)
+++ include/ntuser.h	(working copy)
@@ -2063,7 +2063,7 @@
 NtUserEvent(
     DWORD Unknown0);
 
-DWORD
+INT
 NTAPI
 NtUserExcludeUpdateRgn(
     HDC hDC,
@@ -2470,7 +2470,7 @@
     LPRECT lpRect,
     BOOL fErase);
 
-int
+INT
 NTAPI
 NtUserGetUpdateRgn(
     HWND hWnd,
Index: user/ntuser/ntstubs.c
===================================================================
--- user/ntuser/ntstubs.c	(revision 73520)
+++ user/ntuser/ntstubs.c	(working copy)
@@ -104,17 +104,6 @@
    return 0;
 }
 
-DWORD
-APIENTRY
-NtUserExcludeUpdateRgn(
-  HDC hDC,
-  HWND hWnd)
-{
-   STUB
-
-   return 0;
-}
-
 BOOL
 APIENTRY
 NtUserGetAltTabInfo(
Index: user/ntuser/painting.c
===================================================================
--- user/ntuser/painting.c	(revision 73520)
+++ user/ntuser/painting.c	(working copy)
@@ -2357,7 +2357,8 @@
 
 BOOL
 APIENTRY
-NtUserDrawCaption(HWND hWnd,
+NtUserDrawCaption(
+   HWND hWnd,
    HDC hDC,
    LPCRECT lpRc,
    UINT uFlags)
@@ -2365,6 +2366,36 @@
    return NtUserDrawCaptionTemp(hWnd, hDC, lpRc, 0, 0, NULL, uFlags);
 }
 
+INT FASTCALL
+co_UserExcludeUpdateRgn(HDC hDC, PWND Window /* Wnd or pWnd */)
+{
+    // FIXME: What to do??
+    return ERROR;
+}
+
+INT
+APIENTRY
+NtUserExcludeUpdateRgn(
+    HDC hDC,
+    HWND hWnd)
+{
+    INT ret = ERROR;
+    PWND pWnd;
+
+    TRACE("Enter NtUserExcludeUpdateRgn\n");
+    UserEnterExclusive();
+
+    pWnd = UserGetWindowObject(hWnd);
+
+    if (hDC && pWnd)
+        ret = co_UserExcludeUpdateRgn(hDC, pWnd);
+
+    TRACE("Leave NtUserExcludeUpdateRgn, ret=%i\n", ret);
+
+    UserLeave();
+    return ret;
+}
+
 BOOL
 APIENTRY
 NtUserInvalidateRect(