From 63c15a70eeb95ce57fa49893eb5cab401d984bd5 Mon Sep 17 00:00:00 2001
From: Louis Lenders <xerox_xerox2000@yahoo.co.uk>
Date: Tue, 28 Sep 2010 18:56:40 +0200
Subject: user32: Unlike RedrawWindow, UpdateWindow doesn't accept a NULL hwnd

---
 dlls/user32/painting.c  |    6 ++++++
 dlls/user32/tests/win.c |   15 +++++++++++++++
 2 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/dlls/user32/painting.c b/dlls/user32/painting.c
index 9f02a03..e7ce2ec 100644
--- a/dlls/user32/painting.c
+++ b/dlls/user32/painting.c
@@ -1202,6 +1202,12 @@ BOOL WINAPI RedrawWindow( HWND hwnd, const RECT *rect, HRGN hrgn, UINT flags )
  */
 BOOL WINAPI UpdateWindow( HWND hwnd )
 {
+    if (!hwnd)
+    {
+        SetLastError( ERROR_INVALID_WINDOW_HANDLE );
+        return FALSE;
+    }
+
     return RedrawWindow( hwnd, NULL, 0, RDW_UPDATENOW | RDW_ALLCHILDREN );
 }
 
diff --git a/dlls/user32/tests/win.c b/dlls/user32/tests/win.c
index f1f590c..fa36885 100644
--- a/dlls/user32/tests/win.c
+++ b/dlls/user32/tests/win.c
@@ -6217,6 +6217,20 @@ static void test_rtl_layout(void)
     DestroyWindow( parent );
 }
 
+void test_UpdateWindow_nullhwnd(void)
+{
+    /*test to show a difference between UpdateWindow and RedrawWindow with NULL hwnd */
+    BOOL retval;
+    retval = RedrawWindow(NULL, NULL, 0, RDW_UPDATENOW | RDW_ALLCHILDREN );
+    ok( retval, "Expected 1, got %d\n", retval);
+    SetLastError(0xdeadbeef);
+    retval = UpdateWindow(NULL);
+    ok( !retval, "Expected 0, got %d\n", retval);
+    ok( GetLastError() == ERROR_INVALID_WINDOW_HANDLE ||
+        broken(GetLastError() == 0xdeadbeef) /* win9x */,
+        "Expected ERROR_INVALID_WINDOW_HANDLE, got %d\n", GetLastError());
+}
+
 START_TEST(win)
 {
     HMODULE user32 = GetModuleHandleA( "user32.dll" );
@@ -6316,6 +6330,7 @@ START_TEST(win)
     test_shell_window();
     test_handles( hwndMain );
     test_winregion();
+    test_UpdateWindow_nullhwnd();
 
     /* add the tests above this line */
     if (hhook) UnhookWindowsHookEx(hhook);
-- 
1.7.0.4