Hi Alexander,
you are right, I no longer have the time to improve this addon and I neglected it a little. But I have always tried to fix all the problems that have been reported to me, here or on github. I don't understand what you mean with "the addon does not take over the webpage your are reading". The addon still works good, the only problem I encountered is a little malfunction of the markdown buttons. I fixed it and tested the addon on diaspora v0.7.11.0 with Firefox 67.0.1. I made a video where you can view that it works as expected:
https://arlogn.github.io/easyshare/video.html
Can you explain better what your problem is?