Forum:Layout Builder: What is It?

On my wiki, I'm an admin. The "My Tools" menu from the toolbar has a new item. It's been there for a while now, but it's relatively new to me. I have no idea what it does, and one of those pop-up description things says "This tool is not available on this wiki." What is it and why isn't it available on my wiki?

Roads is a Wikia user! Duh! -_- 16:21, July 28, 2011 (UTC)