Piotr Caban : user32: Don't call IsChild with NULL window in EnableWindow.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: a878f0a02ad553b94b78b907715c691507dea501
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=a878f0a02ad553b94b78b907715c691507dea501

Author: Piotr Caban <piotr at codeweavers.com>
Date:   Tue Mar 21 13:03:55 2017 +0100

user32: Don't call IsChild with NULL window in EnableWindow.

Signed-off-by: Piotr Caban <piotr at codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard at winehq.org>

---

 dlls/user32/tests/win.c | 2 ++
 dlls/user32/win.c       | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/dlls/user32/tests/win.c b/dlls/user32/tests/win.c
index 6e11ff2..915012c 100644
--- a/dlls/user32/tests/win.c
+++ b/dlls/user32/tests/win.c
@@ -3091,7 +3091,9 @@ static void test_SetFocus(HWND hwnd)
     ShowWindow(child, SW_SHOW);
     SetFocus(child);
     ok( GetFocus() == child, "Focus should be on child %p\n", child );
+    SetLastError(0xdeadbeef);
     EnableWindow(hwnd, FALSE);
+    ok(GetLastError() == 0xdeadbeef, "got error %u in EnableWindow call\n", GetLastError());
     ok( GetFocus() == child, "Focus should still be on child %p\n", child );
     EnableWindow(hwnd, TRUE);
 
diff --git a/dlls/user32/win.c b/dlls/user32/win.c
index 4406577..f3b4ef5 100644
--- a/dlls/user32/win.c
+++ b/dlls/user32/win.c
@@ -2171,7 +2171,7 @@ BOOL WINAPI EnableWindow( HWND hwnd, BOOL enable )
             SetFocus( 0 );  /* A disabled window can't have the focus */
 
         capture_wnd = GetCapture();
-        if (hwnd == capture_wnd || IsChild(hwnd, capture_wnd))
+        if (capture_wnd && (hwnd == capture_wnd || IsChild(hwnd, capture_wnd)))
             ReleaseCapture();  /* A disabled window can't capture the mouse */
 
         SendMessageW( hwnd, WM_ENABLE, FALSE, 0 );