This is a GNOME shell extension to allow convenient switching of your monitor(s) refresh rate without having to navigate through the GNOME settings app and confirm each mode change.
The UI is implemented as a GTK window in a separate process from gnome-shell. This made it easier to test, and makes it easier to use in case the display is a TV which overscans in some modes; the window stays open after selecting a mode, whereas a menu would close, and the panel might be off-screen due to overscan, so you'd have to do some blind clicking to find the right icon again. The disadvantage of this design is that Wayland and/or modern mutter don't allow an application to control the position of its windows, so the window tends to appear a long way from the panel icon.
I also intended to include a control for turning fullscreen redirect on and off, but this is more awkward to implement with a separate process, and there was already a Fix Fullscreen Tearing extension which serves very well since I updated it.
