The following steps allow hiding all top menu bars, allowing fullscreen mode for games running in RetroArch (including nes/snes).
Ubuntu 23 / Gnome 45
- Download Hide Top Bar from the Gnome Extensions Store.
- Download latest version of Unite-shell.
- Extract unite-shell to
~/.local/share/gnome-shell/extensions - Open Extensions Manager in Ubuntu.
- Enable both extensions.
- In Unite settings, disable all sliders. Set Hide window titlebars to Always. You can always right-click in the title bar area to show the context menu to close the window.
- Logout/login.
- Run
emulationstation. Select Retropi / RetroArch, Settings, Video / Fullscreen Mode. Set "Start in Fullscreen Mode" to ON, set "Windowed Fullscreen Mode" ON. Go back a level and select "Windowed Mode", set "Enable Window Decorations" to OFF. Go back to the RetroArch option Configuration set "Save on Exit" to ON. Exit RetroArch.
Extensions Manager
Unite Settings