I guess nobody else (chrome, firefox etc) read the Gnome HIG.
Probably best not to add a hard coded action for any keybinding, some user is guaranteed to have a problem with it on an Elbonian keyboard [Dilbert reference].
Instead add a second keybinding action defaulting to `<ctrl>equals` so that it can be unset, modified etc if some user has a problem with it. I think it just needs duplicating [this](https://github.com/geany/geany/blob/04566236d3f9811d55d6c7bcc492b3a60369fd20...) (plus the manual explaining why there are two zooms) :smile: