I tested the desktop options in Debian's installer (using Debian testing). Lomiri appears to be unique in not supporting client side decorations. Even Unity (which isn't a Debian desktop but is an Ubuntu desktop) supports them. Test Case --------- 1. Make sure you don't have gtk-nocsd or libgtk-nocsd0 installed. 2. Install simple-scan. - If you're using Debian or Ubuntu, you can take care of all of that, by running `sudo apt install simple-scan libgtk-nocsd0` - Reboot after making those changes. 3. Run simple-scan (shows in the launcher as _Document Scanner_). It's a gtk4+libadwaita app. Lomiri shows the server side decorations even though the app uses client side decorations and has a close button of its own. Unity ----- {width=745 height=600} Lomiri ------- {width=900 height=551}