Skype icon problem with group chats

Hi,

Docky 2.2.1 bzr docky r1845 ppa running here, ubuntu 13.04 64 bits (and same problem with ubuntu 10.04 64 bits before)

Whenever someone starts a group chat with skype, there is a "1" that sticks forever on the skype icon, even after the conversation is closed / after I quit the conversation, and there is absolutely nothing I can do apart from :
- restarting docky
or
- restarting skype

Skype itself does not show any active chat / missed chat.

This bug is cumulative :
- 2 group chats => the number "2" appears on the skype icon
and so on.

It's not critical, though it's quite annoying

Thanks.