Comment 41 for bug 481541

I'm not sure we've addressed all the issues discussed here, so I'm not marking
this fixed, however the last patch rubs me the right way so I've checked it in
and am minusing this bug for 1.0.

The reason to diverge from the 'load in background' preference here goes to user
intent.

When middle/ctrl+clicking on links on a web page, the general case is that the
user is not done with that page yet, he is queuing up a set of pages to look at
when he's done.

When loading a link from another application such as an IRC client or mail, the
argument is that he's looking to view that link *now* (since he presumably
left-clicked on the link in that application)

When loading a link in the browser targeted at _blank by left clicking again we
can reasonably assume the intent of the user is to see that content *now* not
later, so again focusing it seems a good default.

So there seem to be two "load in background" cases - one controlling whether or
not to select the tab when the user was performing an
open-with-force-in-new-medium-modifier and one controlling whether or not to
select the tab when the user was performing a standard "just let me see this
darned link" left-click. In the latter case, I'd rather not have the user need
to think about what they were doing, and just have what they were probably
expecting - see the page content appear - happen.