User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:29.0) Gecko/20100101 Firefox/29.0 (Beta/Release) Build ID: 20140506152807 Steps to reproduce: 1. Start the browser. 2. Open Tools > Web Developer > Browser Toolbox. 3. From the Browser Toolbox, select the Inspector tab. 4. Use the element picker and pick an element in the browser. Eg. the address bar. 5. The element should be highlighted in the inspector - HTML tree. 6. Select the Console tab and in the command line type $0 and hit enter. Actual results: $0 returns null Expected results: $0 should return a reference to the picked/selected element.