Guideline 5 : Ensure user control of user interface behavior
Checkpoint 5.3 : Manual viewport open only
Allow configuration so that viewports only open on explicit user request.
When configured per provision one of this checkpoint, instead of opening a viewport automatically, alert the user and allow the user to open it with an explicit request (e.g., by confirming a prompt or following a link generated by the user agent).
Allow the user to close viewports.
Sufficient techniques
To satisfy provision one of this checkpoint, configuration is preferred, but is not required if viewports can only ever open on explicit user request.
Normative inclusions and exclusions
If a viewport (e.g., a frame set) contains other viewports, the provisions of this checkpoint only apply to the outermost container viewport.
User creation of a new viewport (e.g., empty or with a new resource loaded) through the user agent's user interface constitutes an explicit user request.