Hello, I found a bug. When you create an entity you can add a behavior to it(Follow is the only one by default). When you want to remove it you click on the cross, a message appear("Ok To Delete"), and if you click a second time the behavior is deleted.
For exemple: http://img827.imageshack.us/i/mantisbug.png/

But after that, if you keep the cursor in the message zone (the rectangle containing the message "Ok To Delete"), the button still be active, and if you click in another time the program crashes. I suppose it's because the button is not removed and on the third click the program try to delete the behavior who have ever been deleted.