i tested and found that it saves that information rightly, but often it was saved only on quitting.
now i fixed this bug.
know, damme, that i had the same suspicious, but i found that groups collapsed often was expanded without noticing when searching contacts via keyboard. I often type the name of the contact i want to chat with, and while i type it, the search stops on the wrong contact until i typed all characters.
When it stops on a contact in a collapsed group, the group is expanded.