Set browser.tabs.insertRelatedAfterCurrent to false.
In Mozilla's Add-Ons Site redesigned I was a bit disappointed, because I wasn't able to see if my favorite add-ons will still work with Firefox 3 anymore. The redesign removed the information about the compatibility of an add-on. A minor revision of the add-ons site has now restored this information. Check it yourself. Visit the NoScript page, scroll down a bit, and there you are: Works with: Firefox: 188.8.131.52 - 3....
Announced in the Mozilla Blog: The add-ons site is now available in a new design. It looks very nice. I have just one problem: Today I wanted to check if my installed add-ons are ready for Firefox 3. The old site had a version information like "1.5 - 3.0b4". This information is gone now.
Good news everyone! Web Developer now supports Firefox 3. See the history and announcement.