how to avoid skype showing chat window when using pidgin?

I may miss the forest for the trees, but I don't know how I can force the skype-pidgin-construct to only show pigding-chatwindows when a new message comes in. There is always the pidgin AND the skype chat which pop up. Can I change that, if yes, what to do?

I'm using Skype 4.1.0.20 and Pidgin 2.10.3 on Ubuntu 12.04.