Compose in new window, window doesn't exit

[Vladimir]

Sometimes, when composing a message in a new window, the window remains behind after the send button has been clicked. The message goes out but the window stays. Force closing the window gives the "Are you sure you want to navigate away from this window, etc" type popup. So far only seen in Firefox but by multiple people.

Anyone seen this or know what causes it?

[palmczak]

We have seen this as well. I do not know what causes it. I still am trying to figure out how to recreate it, currently it appears to be a random issue.