I can consistently reproduce a browser lockup in epiphany by re-sizing the "Title" column in the History window (to try and make it wider). This is on epiphany 3.6.1 in Fedora 18. I had the same problem in the epiphany in Fedora 17 too. While the left mouse button is depressed, the resize appears to be working and the column width adjusts, but when you let go of the mouse the lockup occurs. After this happens, the mouse cursor gets stuck in the "resize" window state and I can't click on anything anywhere else in the desktop.