MClickFocusTab {web link} While using mouse middle-click to open new tabs, with a short- time clicking to open new tabs in background, with a long-time clicking to open new tabs in foreground.

Separate Issue; Your System Details shows;

Installed Plug-ins

Adobe Shockwave for Director Netscape plug-in, version 12.1.9.160 Adobe Shockwave for Director Netscape plug-in, version 12.1.2.152
Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer.

Shockwave Director: Shockwave Standalone Installer / Uninstaller{web link} Shockwave Director Version 12.2.2.172 http://get.adobe.com/shockwave/

Okay, I shouldn't have to install an add on for this to work. I just want to middle click a bookmark and have it open in a tab without switching to it. The same as it did before, without an add on. I don't want to have to remember to "long click" or whatever.

Thank you for the suggestion anyway.

Also I deleted those plug ins. But how did you know about that?

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browser.tabs.loadBookmarksInBackground

Boolean

Focus behavior of new tabs from bookmarks & history

True: When you open a bookmark in a new tab then that tab will load in the background without taking focus from the current tab.

False (default): When you open a bookmark in a new tab then that tab will become the current tab.

Note: you likely want to set this to the same setting value as used in browser.tabs.loadInBackground (Bug 469456) Note: Firefox 1.0.x had a Tabs option for "Select New Tabs from Bookmarks or History"

Other such options are obsolete.

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Okay, cool. Just wondering.

Also that worked! Thank you!

Glad to help. Safe Surfing.