The Social menu does not remember its "collapsed categories" state correctly (or at least not as this user expects or wants).
Suppose that my Online Friends and Offline Friends are both collapsed, and then I uncollapse Online Friends and close the menu. When I reopen the menu, Online Friends and Offline Friends are both uncollapsed. That is, the menu now thinks that I want Offline Friends uncollapsed, even though I never uncollapsed it.
The same goes for collapsing either Friend category, and for collapsing/uncollapsing either Guildmates category. The menu seems to remember a single setting for Friends and a single setting for Guildmates, even though more control is available while the menu is open. This surprises and confuses the user, and seems inconsistent with how other menus in Spiral Knights behave.
(In my case, I almost always want my online friends/guildmates uncollapsed and my offline friends/guildmates collapsed, so this flaw hits me a lot.)