[dart-misc] Element.setCapture() & Document.releaseCapture() not implemented?

[James]

( reposting from other list )
It seems not possible to call :

Element.setCapture()

https://developer.mozilla.org/en-US/docs/Web/API/Element/setCapture

or Document.releaseCapture()

https://developer.mozilla.org/en-US/docs/Web/API/Document/releaseCapture

.. In dart. These are quite useful as they allow mouse capture outside of
the DOM node its self when the mouse moves, and tho this can be done by
adding/removing from the window object this can cause extra text selection
and more etc...

On a related note is there any good way ( in dart ) of unifying mouse &
touch events .. a bit like the PointerEvent
https://developer.mozilla.org/en-US/docs/Web/API/PointerEvent spec but with
support for all modern browsers?