I have been using Tab Utilities 1.5.28.1 with Aurora (FF34.0b2) in my primary profile for about a month now and have never experienced the issue of not being able to use the urlbar. I'll try it on FF33... Hmmm... I do experience the problem in a stock FF33.0 (without other extensions) ... and stock 34.0b2 (without other extensions)...
Ok. After some testing it appears that when using BOTH Tab Utilities 1.5.28.1 and Flagfox 5.0.8 the URL bar works as expected. So a simple workaround at the moment may be to install Flagfox 5.0.8.Upon further testing, this is not sufficient... Interesting... The problem does not appear to have been stated accurately, at least for what I am experiencing:
For me, this problem only exists if trying to use the urlbar for input directly from a page that does not have a URL. Examples of this would be the "Mozilla Firefox Start Page", the page with recent windows which is normally displayed when adding a tab, or about:blank. Thus, the workaround is to not use any of: the "Mozilla Firefox Start Page" as your home page; or the default new tab page or about:blank for new tabs. Alternately, you can click on a bookmark/history (or one of the small images of recently visited pages) to go to a page and then use the urlbar to enter addresses in that tab from then on.
The reason that I have not experienced this problem is that I have Tab Utilities set to open my (user set, quickly loading) home page in any new tabs. Thus, at no time do I use any of the pages which are affected.