user32: Add an invalid window check to SetActiveWindow.

dlls/user32/focus.c

@@ -232,12 +232,18 @@ HWND WINAPI SetActiveWindow( HWND hwnd )
 
     if (hwnd)
     {
-        LONG style = GetWindowLongW( hwnd, GWL_STYLE );
+        LONG style;
 
+        hwnd = WIN_GetFullHandle( hwnd );
+        if (!IsWindow( hwnd ))
+        {
+            SetLastError( ERROR_INVALID_WINDOW_HANDLE );
+            return 0;
+        }
+
+        style = GetWindowLongW( hwnd, GWL_STYLE );
         if ((style & (WS_POPUP|WS_CHILD)) == WS_CHILD)
             return GetActiveWindow();  /* Windows doesn't seem to return an error here */
-
-        hwnd = WIN_GetFullHandle( hwnd );
     }
 
     if (!set_active_window( hwnd, &prev, FALSE, TRUE )) return 0;

dlls/user32/tests/msg.c

@@ -13602,10 +13602,9 @@ static void test_SetFocus(void)
 
     SetLastError(0xdeadbeef);
     old_active = SetActiveWindow((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, "SetActiveWindow on an invalid window", TRUE);
+    ok_sequence(WmEmptySeq, "SetActiveWindow on an invalid window", FALSE);
     ok(old_active == 0, "expected old focus 0, got %p\n", old_active);
     ok(GetActiveWindow() == parent, "expected active %p, got %p\n", parent, GetActiveWindow());
     ok(GetFocus() == parent, "expected focus %p, got %p\n", parent, GetFocus());