This button supports both the
attribute selectors, which can be used to apply different skins to different button states. In particular,
corresponds to the state when captions are visible and
is used when captions are hidden.
To set up a closed caption button that is 28 x 28 pixels, positioned four pixels from the top and 68 pixels from the right edge of the control bar, and displays a different image for each of the four different button states when selected or not selected.