Thanks for the system info, you can get it all in one place by copying the three lines from `Help->Debug Messages`
WFM on:
``` (null): Geany INFO : Geany 1.38 (git >= acb7b066c), en_AU.UTF-8 (null): Geany INFO : GTK 3.24.20, GLib 2.64.6 (null): Geany INFO : OS: Linux Mint 20 (ulyana) ```
What is your locale? Is your keyboard anything other than US Intl? Does XFCE use `Ctrl+.` for anything?