In newer versions of Debian or Ubuntu you may face the error message “Could not detect registered XULRunner to use” in your logfiles, if you want to start Eclipse or an Eclipse based application, which uses the SWT browser widgets. Current Debian Testing (Wheezy) comes with XULRunner 7.0, but you need a XULRunner < 2.0. You can download XULRunner 1.9.1 from the Debian packages site.