Opening "SystemPreferences", then "Desktop & Screen Saver", and then the "Desktop" tab:
I would like to add my own folder holding pictures to display as a background, and to change these pictures in certain intervals.
I am able to add (with the "+" button) on the left the directory which holds by picture, but the checkboxes "Change picture" and "Random order" on the right are greyed out. How can I enable this?