When an active tab is closed in Firefox, the focus moves to the right tab automatically by default. When the last one is closed, the focus shifts to the left tab. This restartless Firefox add-on called TabRestorePre changes the way it works. Instead of restoring the tab that sits next to the active tab–which is about to be closed, it opens or restores the previous active tab.
Now I wish it had some button or keyboard shortcut to enable/disable the function instantly. The add-on will probably come useful in certain situation but definitely not for the entire browsing activity. I know it’s restartless and thus can be deactivated without having to restart the browser, but still a visible button or a hotkey is a more convenient option to have instead of going to the add-ons window over and over again.
For Tab Mix Plus user, you don’t need to use this add-on to have this function because you already have it. Open the Tab Mix Plus option > Events > Tab Closing. On the “When closing current tab, focus” option, click the drop-down button and choose “Last selected tab”. Click OK to activate the new setting.
Tested version: TabRestorePre 0.1.rev21 on Firefox 19