It would seem more intuitive if only the filters a user has access
to are displayed in the timeline view (since clicking filters one
doesn't have access to defaults to the 'all' model filter).
Attached is a patch that I think fixes this. I think with a bit more
work some redundant preconditions could be shaved off.
If this is accepted I'll go ahead and do that.
Reported by Stewart, Mar 29, 2011