I'm using Linux mint 18.3. When I run the AppImage of kdenlive, the application runs but with the full screen by default. I try to disable the full screen from the menu or by typing ctrl + shift + F and it does not work. It continues to appear full screen, the same thing happens with the kdenlive version flatpak in flathub ..
This is solved in the refactoring version. We closed this bug. If it still appears in the latest version, please feel free to re-open it and update the affected version number.