Free app with outlining as good as WordPerfect?

Free app with outlining as good as WordPerfect?

I don't know how many of you have ever used WordPerfect's built in outlining, but let me tell you, it's fast and sweet. Tab to go down a level (e.g. I. to A. to 1.) shift+tab to go up. I guess I could stand slightly different keys. My word processor of choice is currently AbiWord, I think (Windows). If I could integrate with AbiWord or if a newer version has it (I have 2.6.4), that would be great.