usage
The slideshow view is still in an early stage of development with only a basic set of features.
If you don’t need the auto-advance mode, you could even use the sticky preview feature instead.
spacebar             start and stop auto-advance mode which automatically switches
                     to the next images every five seconds by default.
ESC                  leave slideshow mode and return to lighttable view.
+ or                 increase delay between each image.
up arrow 
- or                 decrease delay between each image.
down arrow
left-click or        
right arrow or       switch to the next image of the collection.
right shift-key
right-click or       
left arrow or        switch to the previous image of the collection.
left shift-key
Hint: To take full advantage of your screen size, put darktable into fullscreen mode by pressing F11 and hide the border-controls by pressing the B key.
