There are other add ons to overcome firebug isolation, One of the best tool to verify xpath is Try Xpath add on to firefox developed by larissa9839.

I have given step by step tutorial for how to use Try Xpath add on on **http://selenium-webdriver.com/java/install-try-xpath-selenium-webdriver.php**

Keep up the Awesome work.


regards
Pavankumar Nagaraj