tests: Fix failing window unit test on macOS

Fixes #804 (together with previous commit 979f194f499e76a12ba137c52b3b33f51d7d8e6c)

tests/display/test_window.py

@@ -11,6 +11,7 @@ def test_window_basic(window):
     default_props.set_origin(current_props.get_origin())
     default_props.set_minimized(False)
     default_props.foreground = current_props.foreground
+    default_props.z_order = current_props.z_order
 
     # The rest should be the same
     assert current_props == default_props