Hey, I’ve made a “simple” add-on that redirects these kind of “annoying” popups automatically:
So you do not need to enter your Mastodon handle every time you want to access
Here you can see it in practice:
Getting started
It’s actually easy:
- Install the add-on.
- Go to the settings page and enter your Mastodon ID as you would have in the popup…
- You’re done! Try it out on any page…
This add-on was experimental for some time, but now v1.0 is released! 
Try it out!
Get it for Firefox!
Source
The source code is available on GitHub and I’d appreciate any feedback you might have:
BTW, if you want to re-toot, here is me announcing it:
