[Windows] Titler tool, display real background not working in "directX" backend.
here a forum report about this: https://forum.kde.org/viewtopic.php?f=265&t=165283 to see the correct background is necessary to switch the backend to OPENGL.
similar to issue: #596
opened also a request to make the OPENGL backend the default on Windows before release 20.04 to prevent issues: #604