Arrow keys activate dropdown menu options
unexpected-change-select
Rule
Changing an element's value MUST NOT automatically trigger a change of context, unless the user is adequately advised ahead of time.
Background
When a major change of context occurs - such as a opening a new window, moving focus to another element, a submitting a form - while a keyboard user is tabbing through a page, they may become quite disoriented or, much worse, they may be completely blocked from using the content. Any component that is able to trigger an event when it receives focus must not change the user's context. This will ensure that keyboard users can successfully navigate their way through a page in a predictable manner.
How to Fix
Fix this issue by ensuring that focusing on an option (using the arrow keys to move down the option list) in a