Gallery gets stuck mid-transition when swiping/dragging

[andrewrubin]

Issue

When the draggable prop is set to true, the gallery can get into an in-between state when transitioning between slides. It seems that if the pointer event leaves the gallery area, the gallery still thinks it is being dragged.

Expectation

When leaving the draggable area, any "dragging" flags should be set to false, and the gallery should manage its active index state by transitioning to the nearest gallery item based on the dragged position so far.

[q404365631]

Hi! I'd like to work on this bug. The gallery drag state not resetting on pointer leave sounds like a straightforward fix. I'll investigate and submit a PR soon.