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?