Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1005566 - "Hovering mouse over a link in a webpage causes SeaMonkey to send packets to that link's address."
The update nag screen says this is a security update. I can't find anything specific about that at the [URL], except if the already mentioned "hover bug" is regarded as information disclosure.
Makes sense -- this should be bumped as part of bug 512896 I expect.
Should be fixed already.