The Tabs panel of the Options window is where you'll find all the settings related to how tabs work Select option in list as marked(When I open new link on tab switch to it immediately)

  When I open a link in a new tab, switch to it immediately: When you middle-click on a Web link (or hold down Ctrl while clicking with the left mouse button), the page will be opened in a new tab. That page will not be displayed and will load in a background tab. Check this option to load and display the page in a new foreground tab instead.

Thanks Mohammed, but I already have that option set as you describe. It doesn't apply to middle-clicking the back button!

Try to hold down the Shift key while middle-clicking. That should toggle the default setting as set in Preferences > Tabs.

Thanks cor-el, that does work. But I would prefer to find a way that doesn't require I hold shift, if possible.

Then you need to change the setting in Edit > Preferences > Tab:

• [ ] "When I open a link in a new tab, switch to it immediately"

There are three prefs, accessible via the about:config page, to control the focus if you click a link.

• browser.tabs.loadInBackground (normal links)
• browser.tabs.loadDivertedInBackground (javascript)
• browser.tabs.loadBookmarksInBackground (bookmarks and searchbar)

See also http://kb.mozillazine.org/about%3Aconfig_entries

Thanks, but I know about those, and none of them actually effect behaviour of tabs with the back button.

Check out MClickFocusTab from the Mozilla Add-ons Web Page. A quick click opens a new tab in background, but a long click opens and moves you to the new tab. There’s a lot of good stuff here.