User Agent: Mozilla/5.0 (Windows NT 6.0; WOW64; rv:5.0) Gecko/20100101 Firefox/5.0 Build ID: 20110615151330 Steps to reproduce: Created a Facebook App tab. Then while on that App tab, I wanted to go to a new site, and typed the new URL not noticing that I was on that App tab. Then later I tried finding my Facebook App tab, and I couldn't find it, because the App tab had switched to the other website. I believed the notion of the App tab was that it was always there, but allowing one to navigate away from it can be confusing. Actual results: My original App tab changed to a website that I didn't want an App tab for Expected results: Firefox should not let a user change the URL of an apptab. Links within that URL should stay within the App tab, and the URL shown.
If you only want to disallow changing the URL manually, then that is bug 607266. If you want the new URL to open in a new tab, then vote in bug 598587.