Recently Firefox 3.6 and 4.0 would randomly write over a open tab when I clicked on a link within an email or clicked on a link within my quick tab bar. This is driving me nuts because I may have 10 or more tabs open for reading/browsing or returning to later in the session. Went back to 3.6, no help, fiddled with all the setting in Firefox, IE Tab Plus and Tab Mix Plus to no avail.

I want the option where no tab can be closed unless I close it. Tabs should behave the way the user wants them, not how the software designer thinks it should. Time to look at Chrome 10 and IE 9.

Pinning tabs is potentially a great feature but I too have issues with it in it's current state. Specificaly, I don't like how you can navigate away from the pinned domain.

Addition to the suggestion above, what would be great is if pinned tabs were forced to stay in their domain (example.com/whatever). If you click on a link outside this domain or type another URL in the address bar, a new tab would open.