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.

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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.

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