So if it's a mere internal, we could likely just have an internal handler list we activate in order when the "single" keybinding handler is called.
@b4n, sure we can re-implement signals yet again :) I didn't get to ask @kugel- what his problem was, but my thought was how some things fall back to Scintilla, but those could always be "upgraded" to Geany (but only if the manual is upgraded as well :)