User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20100101 Firefox/13.0 Build ID: 20120601045813 Steps to reproduce: Normally using Firefox 13.0 on CentOS 6 Linux for maybe 20 minutes. Maybe some Java script or so triggers the problem. Actual results: a bug comes up which makes mouse buttons single click only. When it is needed to hold a mouse button it doesn't work. Using a web based selection box can only be done by clicking on it, not moving the mouse, and using the cursor keys to select the item. In fact already many Firefox versions earlier the bug existed, I tried updating many times, but it was never solved. Expected results: The mouse should work as designed in Firefox on Linux. I started testing with Google Chrome on Linux and it doesn't have the problem, it can browse all day without any issue. Closing and re-opening Firefox solves the issue. Opening a new tab / window doesn't !