A: 

I believe you can set your firefox to open new tabs in the background. If you programatically open a new tab it might open it in the background. If anything it might be worth trying.

Perchik
The only thing I can find would be disabling "when I open a link in a new tab, switch to it immediately" under "tabs" in the ff preferences. I already tried that and it doesn't have any effect on that.
Kim
A: 

You found the new tab parameter, so you're just missing the focus thing.

That ought to be window manager-dependent I think. Isn't something firefox itself is responsible for. If there's a pointy clicky tool to tune the way metacity does that then I'm unaware of it.

JosefAssad
+2  A: 

If you set browser.tabs.loadDivertedInBackground to true in about:config then -new-tab will open tabs in the background and not focus the window. This does more than you (or I) want but perhaps it is a suitable work-around for you?

Allan Wind
I don't see how this does more than I want. Care to elaborate?
Kim
A: 

PERFECT! Thanks just what I needed.