[Geany] highlighting custom comment markers

[AC]

> currently there is no generic solution for this.
> There could be a plugin to do something like this, e.g. by setting an
> indicator on such words, like a green or yellow underline or something
> else.

Is there any chance of there being such a setting in the foreseeable future?
If not, how complicated would it be to create such a plugin (I hardly know any
C/C++)?