[MIX] PF comments on Mixed Content - accessible indication and user controls

The Protocols and Formats Working Group has reviewed the Mixed Content 
specification and has two comments:

1) Section 4.3 - UI Requirements 
http://www.w3.org/TR/2014/WD-mixed-content-20140722/#requirements-ux

There is a requirement that the UI have a visual indication as to 
whether the connection is secure or not:


    If a request for optionally blockable passive resources which are
    mixed content is not treated as active content (per requirement #3
    above), then the user agent MUST NOT provide the user with a visible
    indication that the top-level browsing context which loaded that
    resource is secure (for instance, via a green lock icon). The user
    agent SHOULD instead display a visible indication that mixed content
    is present.


It is important to have a requirement that the indication is also 
available to assistive technology. Current implementations have an image 
icon that is not made available to accessibility APIs.

2) Section 4.4 - User Controls 
http://www.w3.org/TR/2014/WD-mixed-content-20140722/#requirements-user-controls

There are some MAY statements about user agents offering controls to 
limit exposure to blockable passive content and active mixed content.  
Such controls need to be available to the assistive technology as well.

For the PFWG,
Michael Cooper