It is not possible write anything to the editor window when I increase IDE height to full screen. The Windows size buttons and menus work and it is possible to end it. If I return the IDE to previous size, it starts to work again. It works at full screen size.
I have installed it into a folder called C:\Program Files\Arduino156, perhaps the IDE protests the wrong version. And it does not help to reinstall the SW.
I have Win 7.