Hey, thanks for the detailed review and the feedback.
Just some remarks to your point:
1.) unfortunately this is the only way to implement it -- I would love to change this behavior, but this is due to technical limitations dictated by the Firefox-API
2.) that's weird (or I don't fully understand the problem). It would be helpful if you created an issue on http://github.com/kesselborn/conex with more detailed information so I can fix this problem
3.) from conex version 0.8.0 onwards, the "Reopen in container" is not a conex feature but a Firefox-native feature and therefore out of my influence realm :(

Hope this helps