user32: Add a couple of tests for WS_EX_TOPMOST.

dlls/user32/tests/win.c

@@ -1857,6 +1857,14 @@ static void test_SetWindowPos(HWND hwnd)
 
     SetWindowPos(hwnd, 0, orig_win_rc.left, orig_win_rc.top,
                  orig_win_rc.right, orig_win_rc.bottom, 0);
+
+    ok(!(GetWindowLong(hwnd, GWL_EXSTYLE) & WS_EX_TOPMOST), "WS_EX_TOPMOST should not be set\n");
+    SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOSIZE|SWP_NOMOVE);
+    ok(GetWindowLong(hwnd, GWL_EXSTYLE) & WS_EX_TOPMOST, "WS_EX_TOPMOST should be set\n");
+    SetWindowPos(hwnd, HWND_TOP, 0, 0, 0, 0, SWP_NOSIZE|SWP_NOMOVE);
+    ok(GetWindowLong(hwnd, GWL_EXSTYLE) & WS_EX_TOPMOST, "WS_EX_TOPMOST should be set\n");
+    SetWindowPos(hwnd, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOSIZE|SWP_NOMOVE);
+    ok(!(GetWindowLong(hwnd, GWL_EXSTYLE) & WS_EX_TOPMOST), "WS_EX_TOPMOST should not be set\n");
 }
 
 static void test_SetMenu(HWND parent)