You could request it at the Scintilla project.
@eht16 How would those options work with Scintilla GTK backend which calls GTK rather than calling the windows API directly?
Maybe Neil finds a way to implement the necessary bits in a different way for the GTK backend on Windows. Since I have no clue about what's necessary for this, I'm just optimistic that there is a possibility :).
I don't suppose there is any chance you can test with GTK3 Geany on Windows?
I won't test it with GTK3 on Windows as I'm convinced it won't make a difference and so I save me the efforts.
It has to happen one day :).
Ha, I missed that little voice in my head reminding me about this...:D. Actually, a few days ago I started playing with a Docker image to cross-compile Geany using MSYS2. Ideally we can get the full game into the container: git clone, compiling, bundling, creating the installer. The first half is already done. And while doing this, I'll switch to GTK3 finally (and x86_64 only).