The Auto Activate setting applies to interactive elements that remain active after they are pressed. These include the slider, scroll bar, scroll box, and text input.
When Auto Activate is set, an element automatically activates when navigated to with the directional keys, and deactivates when navigated away from with the directional keys. The user does not need to press the Enter and Back keys to activate or deactivate the element.
The UI must be designed so that a user cannot get stuck on an activated element. For example, a horizontal slider that is set to automatically activate should not have another interactive element to the left or right of it. This is because pressing the left or right key on an active slider moves the slider handle.