User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) Opera 7.54 [en] Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.5) Gecko/20041217 I made a post at http://forums.mozillazine.org/viewtopic.php?t=199507 . As far as I can tell from a web and usenet, nobody has gotten this option to work yet. A search for "windowopen" didn't find much in Bugzilla, but this is the bug that's keeping me in Opera. Reproducible: Always Steps to Reproduce: 1. Go to just about any phpBB, vBulletun or UBB forum 2. Find a post with a link in it 3. Click Actual Results: New window spawned Expected Results: New tab spawned

No wonder, there is no backend for this pref :). As a workaround you can do one of the following: 1.) Use middle click, then the link will open in a new tab 2.) Use Ctrl+left click, will do the same as 1.) 2.) Add user_pref("browser.block.target_new_window", true); to your user.js, then it will open such links in the same tab/window. *** This bug has been marked as a duplicate of 105547 ***