Click on the View Menu, then Full Screen. The image will be displayed centered on a black background, which fills the entire screen. Move through the images in the current directory using the space bar or right mouse button for the next image and backspace or left mouse button for previous.
To cancel the full screen mode, press the Enter or the ESC key. If you click with left mouse button in the upper left or upper right corner, the full screen mode will also be canceled.
The current display option can be changed temporary at any time with the keys 1, 2, 3, 4, 5 and 6.