I am running notion on Ubuntu 12.10, and Firefox 18.0.1. I use tmux, bash and xterm in case it matters. The bug occurs I run selenium-server 2.29.0, and run acceptance testing. After the testing is complete Notion no longer works. Everything looks normal except none of my frames are highlighted, and I cannot find any combination of keystrokes to active any of the windows. Also F12 no longer works so I cannot, logout or restart notion.
The testing I am running is Yii's default acceptance tests, specifically the file in protected/tests/functional/SiteTest.php. I use phpunit to run it.
In order to regain control I need to press CTRL-ALT-F1 and pkill firefox. After I do that one of my frames becomes active and everything returns to normal. If I instead pkill java, then I will need to close notion to regain control. pkilling firefox when java is not running will have no effect.
Please let me know if there is any of details you need.