Stupid usability problem of the day: I use some programs that bind ctrl-backspace to delete-previous-word, and others that use alt-backspace. Yesterday, I was typing in something and hit ctrl-backspace to delete the preceding word. That didn't work, so I typed alt-backspace instead. Or at least I tried: I failed to let the ctrl key come up properly, so I inadvertently hit ctrl-alt-backspace instead. Bye bye X.