If you mean the Gmail message list, those are not normal links. When you click one of those rows, a script runs that normally opens the message into the same tab. Holding Command (or on Windows Ctrl) while clicking diverts the content to a new tab, but the script seems to override the normal "open link in a background tab" behavior.

Is there a workaround... hmm... yes, I think so! Give this a try:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste tabs and pause while the list is filtered

(3) Double-click the browser.tabs.loadDivertedInBackground preference to switch it from the default value of false to true -- the line should turn bold

Then in your Gmail tab, try again. Success?

I wasn't able to test on the newer Inbox layout.

I just noticed something really interesting. When I logged out of Gmail, I got a message asking whether I wanted to leave the page and I said yes. Instantly, all of the messages I had opened in new tabs using Ctrl+click closed. How do they do that?

Thanks! Can you think of other situations where this config change would affect how it works? I.e. will the change in browser.tabs.loadDivertedInBackground only affect this specific situation, or will it cause all link clicks to open in the background whether they're from Inbox/Gmail or otherwise?

I think the other, similarly named, preferences address most other situations:

• browser.tabs.loadInBackground => when you open a regular link in a new tab using Ctrl+click (or right-click > Open in a New Tab)
  • default = true, do not make the new tab active
  • In the Options dialog/page, this is controlled by the "When I open a link in a new tab, switch to it immediately" setting.

• browser.tabs.loadDivertedInBackground => when you divert a script-generated new window to a new tab using Ctrl+click
  • default = false, make the new tab active

• browser.tabs.loadBookmarksInBackground => when you load a bookmark in a new tab using Ctrl+click (or right-click > Open in a New Tab)
  • default = false, make the new tab active

Thanks so much for the additional details. Very helpful!

Also - it does work - applied it and it now opens tabs using command-click into the background from both Google Inbox and Gmail.

I ended up disabling as it treats links the same way if they're from outside apps like the Twitter app or anything like that. Picking the one that will be wrong less often. It would be awesome to do something that targeted the Gmail/Inbox thing more specifically, but that might not be possible. Thanks for the info!

Hmm, I didn't test that.

You could force external application links in a separate window as a workaround, but if you like all your tabs in one window, then you'll be even unhappier.

If you decide to try that:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste link.o and pause while the list is filtered

(3) In this case, experiment with setting (C) to two. The others are here for future reference:

(A) browser.link.open_newwindow

3 = divert new window to a new tab (default) (checked*) 2 = allow link to open a new window (unchecked*) 1 = force new window into same tab

* First checkbox in Options > Tabs (Firefox 38: Options > General)

(B) browser.link.open_newwindow.restriction - for links in Firefox tabs

0 = apply the setting under (A) to ALL new windows (even script windows) 2 = apply the setting under (A) to normal windows, but NOT to script windows with features (default) 1 = override the setting under (A) and always use new windows

(C) browser.link.open_newwindow.override.external - for links in other programs

-1 = apply the setting under (A) to external links (default) 3 = open external links in a new tab in the last active window 2 = open external links in a new window 1 = open external links in the last active tab replacing the current page