In addition to the more or less fixed elements of the Ennova interface there are a number of dockable windows, such as the Cut Plane Window above. These windows can be closed so that the don't appear anywhere; they can be moved to a different place in the Ennova main window; or they can be moved out of Ennova main window and can stand alone as their own windows on your desktop. If you have closed one of these windows and want it back, right click on the title bar of the Ennova main window and a list all of the dockable windows will appear. Click on the one that you want to see and it will appear.