Autofocus should not surprise the user

[chaals]

In Autofocusing a form control: the autofocus attribute, inserting a control with autofocus has the step

If the user has indicated (for example, by starting to type in a form control) that he does not wish focus to be changed, then optionally abort these steps.

There needs to be a better explanation of when autofocus shouldn't change the focus. In particular, dragging around user focus can be malicious, and is anti-user behaviour.

So when a user has set a browser preference, or where the user has manually focused a form control, the steps should always be aborted.

This is https://www.w3.org/Bugs/Public/show_bug.cgi?id=13572
@cyns

[LJWatson]

Ping @stevefaulkner because this seems to be addressed in your recent autofocus warning commit?

[stevefaulkner]

@LJWatson I think the warning and associated UA requirement covers this, so closing.