If I click with the mouse just to leave a cursor on the location window, I can delete the previous URL and type in a new one. If I just run the mouse while left-clicking it to select text and then delete it, Mozilla (1.6) crashes. I tested it under KDE, Blackbox and XFCE4. After some minutes, it returns to life, but while waiting it just looks as it crashed. I have Gnome installed too, and Konqueror. This does not happen in Konqueror.
My Konqueror has a bug of its own too. See http://bugs.gentoo.org/show_bug.cgi?id=52429
Actually, it happens when starting Mozilla. After the momentary hang when first trying to type or delete anything with the keyboard, it returns to normal and lets me select, delete or type. But if I quit Mozilla and start it again, the same happens: If I try to edit any text window (except those in webpages), Mozilla hangs and then returns after a while.
Not able to replicate this behavior. If this occurs with the version currently in portage, please reopen with system stats.