In the first additional comment of that wish (
http://bugs.kde.org/show_bug.cgi?id=65176) Stefan Gehn suggest that if you have questions to email the kopete-devel mailing list. They would most likely have an educated answer for you.
Kind of off topic, but are you certain there's a standard stating that instant message applications must close pop-up windows with the escape key? It might be common practice, and it probably makes a ton of sense, but I wasn't aware of any such standard. (Then again I'm not aware of a lot of stuff
)
Cheers.