I tried to edit my layout but found that the editor is broken. Part of the layout was cut off and there was no scrollbar. There were no links to add page elements. If I placed my mouse above a page element I would get the four arrows cursor for moving but I couldn't move elements. This problem existed in Firefox 18.104.22.168 without any extensions and in Internet Explorer 7.0. I found a known issue which seemed to relate. I could indeed scroll in IE by selecting text, but that didn't work in Firefox, and I was still only able to only edit or delete elements.
I fixed the issue by going to "Pick New Template" and reselecting my current one. The layout editor works perfectly now. I wish I could add this as a comment to that known issue page.