In this post, Antoni Dol experiments with a button to demonstrate how FocusVisualElement can be used.
The FocusVisualElement is the equivalent of the dotted line that you see in Windows interfaces and on browser pages around an object on the page that “has the focus”. This means that it will receive the input a user is giving with a mouse, keyboard or touch. Actually, web designers don’t really like these dotted lines, because they degrade the look of their interface. It may disturb the carefully crafted look and feel of the page. But this FocusVisualElement has a function.