OK, the screencast is very blurry so I can't read it well and see what's happening (and in the first place, I don't even know what exactly it should do). In any case, it's most probably a GTK bug and not a bug of Geany itself. I made some more recent builds with newer versions of GTK which might help:

Geany 1.38: https://download.geany.org/snapshots/geany-1.38_osx-5.dmg https://download.geany.org/snapshots/geany-1.38_osx_arm64-2.dmg

Geany 1.39git: https://download.geany.org/snapshots/geany-1.38_osx.dmg https://download.geany.org/snapshots/geany-1.38_osx_arm64.dmg

Another thing you can play with is this settings in `~/.config/geany/geany_mac.conf`

```ini # no value: don't use any IM module; module name: use the specified module, e.g. 'quartz' for native macOS behavior, for complete list of modules, see Geany.app/Contents/Resources/lib/gtk-3.0/3.0.0/immodules, use without the 'im-' prefix im_module=quartz ```