...Use the toolbar to access basic commands like: image slideshow, adjust zoom, rotate, delete, crop or resize the image, sort the list or access the program settings. Move the mouse near the left or right side of the window to show the arrows and select the next or previous image. Move the mouse over the buttons to see a short description or over the thumbnails to see more information.
By default, the viewer starts in full screen mode but it can be switched to windowed mode by pressing F11. Also, you can press Enter to hide or show the toolbars, Space to start the slideshow or Escape to exit the program. ...