User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0 Build ID: 20140927030204 Steps to reproduce: Enable e10s. Open two pages in e10s mode. Try drag one out of FF. To create new window. Nightly 35.0a1 (2014-09-27) and yesterday version too. Actual results: Tab is not dropped at new window. Stay at same window and drop opens a new window with an empty tab. Expected results: Drag and drop correctly.