user32: Add an invalid window check to SetFocus.

dlls/user32/focus.c

@@ -259,6 +259,11 @@ HWND WINAPI SetFocus( HWND hwnd )
     {
         /* Check if we can set the focus to this window */
         hwnd = WIN_GetFullHandle( hwnd );
+        if (!IsWindow( hwnd ))
+        {
+            SetLastError( ERROR_INVALID_WINDOW_HANDLE );
+            return 0;
+        }
         if (hwnd == previous) return previous;  /* nothing to do */
         for (;;)
         {

dlls/user32/tests/msg.c

@@ -13573,10 +13573,9 @@ static void test_SetFocus(void)
 
     SetLastError(0xdeadbeef);
     old_focus = SetFocus((HWND)0xdeadbeef);
-todo_wine
     ok(GetLastError() == ERROR_INVALID_WINDOW_HANDLE, "expected ERROR_INVALID_WINDOW_HANDLE, got %d\n", GetLastError());
     while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) DispatchMessage(&msg);
-    ok_sequence(WmEmptySeq, "SetFocus on an invalid window", TRUE);
+    ok_sequence(WmEmptySeq, "SetFocus on an invalid window", FALSE);
     ok(old_focus == 0, "expected old focus 0, got %p\n", old_focus);
     ok(GetActiveWindow() == parent, "expected active %p, got %p\n", parent, GetActiveWindow());
     ok(GetFocus() == parent, "expected focus %p, got %p\n", parent, GetFocus());