After installing fresh "Ubuntu 22.04.3 LTS" I found one of my docker environment broken.
By previous setup containers should see each other by it's host names which is configured in traefik.
Error was cURL error 7: Failed to connect to test.my-docker.localhost port 443 after 0 ms: Couldn't connect to server (see https://curl.haxx.se/libcurl/c/libcurl-errors.html) for https://test.my-docker.localhost/
The UI of xscreensaver window is a bit old and not so retro as it could be. Unfortunately there is no way to customize the window view mode and elements placement (except rewrite it to your needs). But there is a field for experiments with colors and sizes for some elements.