Howto create a filter bar?

I would like to create a filter bar like the one in the Mail app:

Do you have any suggestions on how I cou开发者_高级运维ld do?

My application is targeted only at OS X 10.7+, so I'd really like to use the most modern method available.

Thanks.

MGScopeBar is an open source component that will mostly do what you want. The appearance is not exactly the same, but you could easily change that.

That is called FavoritesBarView in the Mail application. it looks like its source code exists in webkit source code.