Sorry, I should have specified those things, mind fart on my part.
`geany 1.37 (git >= fe7d2f87) (built on 2020-03-21 with GTK 2.24.32, GLib 2.62.1)` As it says, it is a custom build - but not very custom, and certainly I've not been messing with GTK stuff.
` lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 19.10 Release: 19.10 Codename: eoan `
If it's not reproducible I might have a closer look myself.