I assume Geany ships Scintilla in its codebase?
I hope building it using this is fine? It would be the most convenient and cleanest way for me to install the git head. https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=geany-git
The other thing that I think I will need is some sort of test setup, other applications to test this with. Probably also a way to inspect the different clipboards. Suggestions regarding this are welcome since I do have other applications that cause me trouble which I will have to debug separately (c/p from vim or terminal (urxvt) in general).