Hello :),
it seems that there is a bug when you press the “Show target” button/checkbox-
a new empty window opens whenever the checkbox /button is clicked.
the new window needs to be manually closed because if it is open, you can´t work further.
Thank you!
It is an old bug. Please download the latest distributive from our website to get rid of it. By the way x64 version is released today! 
many thanks the new version solves that and the x64bit is a nice addition 