Hi!
I love the concept of containers but as I began using them, I thought they worked a way that they finally did not.
At first I thought that the assigned tabs to a certain container would kind of remember them. Another way of bookmarking them. But as soon as you close a group or a tab within the group, they are gone.
My best example to understand what I mean is the banking container.
I log on certain websites for my banking business. They are always the same, indeed.
I thought that opening a container would call all the tabs I previously opened before.
Since I do business with always the same banking institutions and sites, I thought that a container remembering a set of established tabs calling the same sites would be nice.
Long life to Mozilla!