https://sourceforge.net/p/geany-plugins/feature-requests
Minimap is actually not that hard to make, I started writing a plugin to do this a while back but stopped working on it due to the fact that I find it annoying and would never use it myself (I disable it in SublimeText2 even). If someone wants to work on it, I might be able to find the code I started with.
I had a quick look at it yesterday too (it sounded interesting). One problem I ran into was that it seems pretty hard to add widgets to the notebook page of a document.
How did you solve this in your attempt, where did you put the minimap widget(s)? Having one minimap widget per document tab seemed like the right solution to me, but it wasn't very easy to implement.
Just wondering, not sure I'll work any more on the minimap but it was kind of fun to try. :)
Regards,
/Emil