Amazing expansion. It's as simple as possible, but it's exactly what I need. I just need to open the right sites as quickly as possible in two clicks in the containers I need! Thank you very much. However, there is a request.. all containers are mixed and scattered. Despite the fact that I have consistently added them, they themselves change their position as new ones are added. Dear developer, please add manual sorting of containers so that they can be fixed in place. Or something like a "Pin" that prohibits any movement. I used about 20 different containers and they all moved to different places on their own, even when I tried to edit them, their location changed and it became more difficult to navigate.

Excellent. Thanks to the developer. but there is a bug when displaying marked containers.
a bug here:
//Iterate over the context we have saved for the site and check off the box

** corrected as below **
for (let columnCounter = 2; ...

Can you design icons for light mode? Thank you.
https://imgur.com/Hl3c9SR

This is helpful for me, but is it possible to add the title of the url instead of showing the full url, thanks.

2022/02/22 update: thanks, updated.

I just needed this! Works perfectly! Thanks

Please add a delay setting. Ex. 1-3 sec between each tab opening

I think the multi-account container-list for open in new'option would includes by authors this as to toggle selection on all the names. That is, "Open Link in New Container Tab"-option will show a toggle selection system. This is betterment, Your nice creation also to do so- I find it my dreams up to date. For certificate expired, container-opener does not work in fx57 yet, only by debug-install'option.
Edited Next: hotfix update fix.xpi have been solved for expired.crt that I found later. Thank you