From MozillaZine Knowledge Base

browser.link.open_newwindow must be set to 3 (redirect links opening in new windows to tabs) for this preference to have an effect.

For me, it's set to 1, and seems like .restriction has effect. Not going to touch the page, since I'm not particularly familiar with all those tab-related prefs. --asqueella 22:29, 14 January 2006 (UTC)

Went through and tested all 18 combinations and posted the correct observed behavior. Thanks for the heads-up. --Unarmed 23:35, 14 January 2006 (UTC)