This is a follow-up from bug 390238. Now that onbeforecut/copy/paste events are supported (bug 280959), the testcase is hanging Mozilla. From bug 390238, comment 7: > I like your hang testcase. Please assign the new bug to me. Because it loops > via .focus(), it never hits the "A script on this page is making it run slowly" > error. Would the same hang happen if it was onfocus, rather than > onbeforepaste? No, it doesn't hang when using onfocus, so there seems to be some loop protection happening there for that case. Note that I had to use 3 text inputs to get the hang, because with 2 text inputs, I would not get the hang, but an error in the error console saying "Too much recursion".

This is worksforme now, because bug 418457 removed support for onbeforepaste events.