It is almost an independent module, it doesn't seem to be interconnected with other GTK internals. If it'll ever be removed (I highly doubt it will), you can copy the latest available version and it'll continue to work locally.
Nor is it likely that Geany will support a fork of an internal part of GTK.
Also one of the contributors had a first look at accelerators and came upon the stumbling block that they only allow one closure per binding, not sure if they found any workaround to that.
I don't get it, what is the problem here? Does current implementation allow to have multiple actions set for one hotkey?
I havn't discussed it with them, but my expectation is that several things (Geany and Scintilla) and an unknown number in plugins connect to the keyevent signal. So plugins can override Geany and Scintilla is a fallback for Geany. Not sure how the accelerators code fits into this.
Downgrading the UI
Sorry, but who will really even notice that particular change?
Since the keybinding activates the menu making it inactive is what stops it trying to copy when there is nothing selected. And while you may understand that, there are many inexperienced users of Geany.
I agree about total remakes, but the approach with accelerators doesn't require many changes in my view.
Pull requests are welcome, though I suggest you announce a Gtihub fork where you will be doing the work so people can watch and contribute as you go, rather than just dropping a commit bomb when you have finished.
Note, I am not a fan of the current keybinding implementation, and have ranted about it in the past, but I am even less a fan of major changes to stable codebases.
Are you serious? Surely you don't want to say there isn't many people who use non-Latin alphabet. But it is less likely they're able to report bugs in English, yet you already have two other opened issues about this.
Acknowledge the issue that its difficult for non-English users to be noticed on a purely English project, but unfortunately its also all anybody has to judge the relative usage.
You don't have an alternative layout yourself, do you?
Correct, but the problem is not just an alternative layout, but the alternative has to change the keyval for the same key. It is also why I can't do anything about testing this. That is also the case for many if not all other contributors (some do use multiple languages, but for them c is still c not for example Cyrillic_es), if it was a problem for them it would have been raised before this.