This can be accomplished by providing a user style sheet, using the defined mapping of cues to pseudoelements.

I have no idea which part of
   http://www.w3.org/WAI/PF/HTML/wiki/Media_Accessibility_Requirements#System_Requirements
...I'm supposed to look at.

I also don't really know which captions this is referring to. Is this request in the context of WebSRT, or in the context of a user agent rendering in-line captions?

In what sense is the user _not_ in control here?


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Status: Did Not Understand Request
Change Description: no spec change
Rationale: I don't understand. Could you elaborate?

The bug triage sub-team adding the a11yTF keyword; John could you please follow-up?

Bug triage sub-team assigning to John Foliot to provide the needed info.

UAAG20 has this covered

 1.1.3 Display of Time-Based Media Alternatives:

For recognized on-screen alternatives for time-based media (e.g. captions, sign language video), the following are all true: (Level AA)## DONE 2 August 2012

a.    Do not obscure primary media: The user can specify that displaying media alternatives doesn't obscure the primary time-based media; and

b.    Do not obscure controls: The user can specify that the displaying media alternatives doesn't obscure recognized controls for the primary time-based media; and

c.    Configurable text: The user can configure recognized text within media alternatives (e.g. captions) in conformance with 1.4.1.

Note: Depending on the screen area available, the display of the primary time-based media may need to be reduced in size to meet this requirement.

1.1.4 Default Rendering of Alternative Content (Enhanced):

For each type of non-text content, the user can specify the cascade order in which to render different types of alternative content when preferred types are not present. (Level AAA)   

1.1.5 Size and Position of Time-Based Media Alternatives:

 

The user can configure recognized on-screen alternatives for time-based

media (e.g. captions, sign language video) as follows: (Level AAA)

 

a.    The user can resize the media alternatives up to the size of the user

agent's viewport.

b.    The user can reposition the media alternatives to at least above,

below, to the right, to the left, and overlapping the primary time-based

media.

 

Note 1: Depending on the screen area available, the display of the primary

time-based media may need to be reduced in size or hidden to meet this

requirement.

 

Note 2: Implementation may involve displaying media alternatives in a

separate window, but this is not required.