in the pointer interaction, track touchend/touchcancel?

[Fil]

There seems to be room for improvement of the pointer interaction on mobile.

I've received two reports on the same day that:

• "can't get rid of" the interactive tip (reported by @CobusT)
• the "pointer-driven mark" does not reset on https://observablehq.com/@observablehq/plot-pointer-driven-marks. (reported by https://mastodon.online/@rkaravia/113193992773718603)

In fact you can end the pointer interaction by "holding and dragging out", but it's not very natural. On mobile we'd expect ending the touch gesture to end the interaction (unless it's sticky, after a tap maybe?)?

[Fil]

related #2157