I'm not sure if this is a bug report or a feature request - but I think it is the latter...
I would find a horizontal scrollbar in the categories tab of the tree pane quite useful, especially if the categories structure is more complex and deeper than in this screenshot/example:
- no scrollbar.jpg (109.05 KiB) Viewed 938 times
Such a horizontal scrollbar actually does exist in the two other tabs of the pane ("Favorites" and "Folders"), so why not in the categories tab? It would make the categories more readable if the whole pane is rather narrow, thus not forcing the user to enlarge it horizontally.
And I certainly have to admit that this is definitely a non-dramatic issue - just a small suggestion and an idea...
