We did a sidebar with PXSourceList (subclass of NSOutlineView). On Lion, there is the text "show" or "hide" for group items when you hover these. But unfortunately, when the sidebar size is to small, this text is overlapped with our own title of the item. The same problem is seen in the current iTunes implementation.
As an illustration, see:
But other macosx applications like Finder or Mail hides a part of their own text and add "..." in order to prevent the overlap:
Is they any way to achieve the same result in an own application?