IDEA 15 - Windows popping on multi monitor setup

I'm uing IDEA15 on a mac with two monitors. I have the main window with the editor full size on the first monitor, the project structure, debug and CVS-Info in 3 Seperate Windows on the second Monitor. On Previous 14 versions this worked very well, however with IDEA 15 the 3 seperate windows randomly disappear and move onto the primary monitor in front of the main window.

Does anybody have an idea how to fix this? Should i write a bug report?

Greetings
Sebastian