Mozilla Firefox 1.5.x before 1.5.0.12 and 2.x before 2.0.0.4, and SeaMonkey 1.0.9 and 1.1.2, allows remote attackers to spoof or hide the browser chrome, such as the location bar, by placing XUL popups outside of the browser's content pane.  NOTE: this issue can be leveraged for phishing and other attacks.