As for changing the API, the usual solution would be to add the new parameter and provide a default argument for it (and the default would be the "normal" behaviour, so other plugins don't even notice that there is something new). If I am not mistaken, Geany is implemented in C, and C doesn't have the feature of default arguments builtin, but there are several ways to achieve this functionality in C too.
All the other arguments you gave, are really convincing, so IMO, the best (and maybe easiest) way would be to extend the API. --- Reply to this email directly or view it on GitHub: https://github.com/geany/geany/issues/815#issuecomment-165033707
