How to add extra property to window object

Hi all, I'm trying to write a Firefox extension that adds an extra property to the window object that Web pages' scripts have access to. As you know, currently, scripts in Web pages can access such objects as window window.document window.navigator

PropertyPermission denied

Hi, if my javascript generates the following exception: java.security.AccessControlException: access denied (java.util.PropertyPermission java.io.tmpdir read) which privilege should I ask for? I've already tried: netscape.security.PrivilegeManager.enablePrivilege(UniversalXPConnect