1. Run TBB v3.5.3 2. Click on a link to download an archive or any file type not natively handled by the browser 3. Wait for the download to complete 4. Observe that <random>.ext.part file is created containing entire file contents in the system's %temp% folder. 4. In the Open/Save dialog box click Cancel. 5. Observe that the temp-created file is not removed. 6. Close Firefox/TBB. 7. Observe that the temp-created file is not removed. Firefox 28's Private Mode does not have this bug. I observed this bug in TBB v2.x as well. **Trac**: **Username**: ericlaw