How to switch over from fullscreen mode to windowed view mode and vice versa?
To switch between full screen and normal display modes, just do the following one-step actions:
How to enter full-screen view mode?
At the center of the book, click the full-screen button (the dark circle) to go to full-screen mode. The application will expand to full screen.
How to return to the windowed view mode?
Press Esc to exit full screen and return to the full-size window. The Esc key lets you quickly re-enter normal display mode.