I make heavy use of the speed dial add-on. It won’t work in this addition. Fortunately I have the regular addition of Firefox, which I have immediately disabled checking for updates. This last update to FF Developer’s edition broke too many things, plus now has a very ugly interface. As soon as I can move my bookmarks, I an uninstalling it. If this happens to FF regular, I’ll switch to Chrome.
Change the interface back ASAP! This new interface isn’t good enough to say it sucks.