I've come across a use case where it would have been nice to replicate
the <audio> element across frames using postMessage to communicate
information.
I know that youtube uses cross-frame messaging quite a bit.
Pseudo-code:
<body>
<audio controls>
<iframe>
<!-- inner src -->
<audio>
</iframe>
</body>
While there are many ways to handle the case, it would've been swell to
be able to proxy information through frames via postMessage. Native
<audio controls> implementations are immature, webkit's works poorly
with width/height. It'd still be nice to use it as often as possible.
[css] appearance: none is one means of adjusting the presentation model.
I think that media "controls" is another.
The <audio> element comes with sufficient apis to implement its feature
set, and it has plenty of vendor-specific pseudo-selectors for the
shadow dom.
It has a combination of buttons, progress meters, ranges (a volume
slider), and a popup (also the volume slider). It's a good place to look
when fully implementing appropriate ARIA hooks, and a good reference for
how vendors have tried to handle a complex widget.
-Charles
