minimize all closed dialogues into a folded list

[Iwan-Ittermann]

Is your feature request related to a problem? Please describe.
the dialogue list is cluttered, especially by ended dialogues. No action can be taken in closed dialogue.

Describe the solution you'd like
Inside the dialogue list, there could be sub lists for active, closed and requested dialogues. The lists are folded by default. Every list has an "expand" button. If the user clicks it, the sub list is expanded.

Describe alternatives you've considered
Closed dialogues could simply be removed from the dialogue list. Yet users might want to re-read their dialogues. They could do this by clicking on the edges/lines, but then the user would need to find his opinion and find the edge.. very time consuming.

Additional context
This evokes the idea, if there should also be a list for the opinions of the user.