Open popup in a tab

Open popup in a tab

* in address bar enter: about:config

set the following prefs:
browser.link.open_external set to 3 (should already be)
browser.link.open_newwindow to 3
browser.link.open_newwindow.restriction to 0 (zero)
To avoid your window resizing you need to restrict javascript from resizing windows. This can be done via the normal Firefox preferences under Tools > Options > Content > Allow JavaScript > Press Advanced.

(source: http://forums.mozillazine.org/viewtopic.php?f=7&t=762235, thx to Euchre)