Perhaps related to connecting/disconnecting from an external monitor, but I find that every now and again on latest Firefox Nightlies, OSX 10.9.3, the element on the page responding to :hover is up and to the left of where the mouse pointer is; thankfully click still acts on the object beneath the pointer. So if I'm pointing at, say, a message in my Gmail inbox, the grey "grabber" appears 3 messages above it. Clicking will activate the message I'm pointing at, though. (This may end up being a Core bug)

(Restarting the browser repairs the problem, FWIW)

Good STR will be much appreciated :-) In the meantime a fix for bug 1013852 has just landed on mozilla-inbound, and should appear in tomorrow's m-c nightly or the next day's. Once it does appear in a m-c nightly, please try it out.

It's hard to understand how this is related to bug 1013852. Boris, why did you set this dependency?

Hmm. I thought this was the bug I was seeing with hover randomly not taking effect at all, but reading more carefully shows I was probably wrong. We should still retest once bug 1013852 is fixed, assuming this is sort of reliably reproducible.

My fix for bug 1013852 has just appeared in its first m-c nightly -- today's.

Hi, I haven't managed to reproduce this issue on the latest Firefox release (43.0.4) nor the latest Nightly (46.0a1). Is this issue still reproducible on your end? Thanks, Cipri

Since the reporter didn't provide the requested information the fact that I could not reproduce the issue, I will mark this issue as RESOLVED WORKSFORME. If you still encounter this problem, please feel free to reopen this bug, or file a new one.