On Focus

Understanding WCAG2.0

Just by receiving focus, do not cause any situation change. An example of a malfunction that a modal window that opens automatically when receiving focus and a page movement occurs when receiving focus. Such behavior is difficult for users to predict and is hard to handle.

Principle Understandable Information and the operation of user interface must be understandable.
Guideline Predictable Make Web pages appear and operate in predictable ways.
Criterion On Focus
(3.2.1 A)
Neither component causes a change in context when it receives focus.

URL of Techniques for WCAG 2.0