Created attachment 8520281 [details] crazytabs.gif User Agent: Mozilla/5.0 (X11; Linux i686; rv:35.0) Gecko/20100101 Firefox/35.0 Build ID: 20141110004002 Steps to reproduce: 0. Download firefox aurora 1. Run `firefox -p`, create empty profile and start it. A window with two tabs opens. 2. Resize it to match the size on attached image. It was a default window size for me. 3. Click the "hamburger" button, select "Customize". Third tab opens. 4. Click Themes / Get More Themes. Tab 4 opens. 5. Switch back to the about:customizing tab. See tabs going crazy. Probably important things: * window size is important * about:customizing must be tab 3 of 4 * firefox developer edition theme must be active * mouse should not hover the tabs Actual results: crazytabs.gif Expected results: Expected results: Firefox not taking 100% CPU, tabs not moving left-right.
Brian, do you have time to look at this? :-(
This is potentially a dup of 1096542. I'll take a look.
After looking further into this, I believe it's the same problem as 1096542