tree 66ec4140ecac50d81f8e521204e315183ec83f35
parent 43664f62866c05a5d7d6b324904f75995d37bba7
author Sean McCullough <banksean@gmail.com> 1745202797 -0700
committer Sean McCullough <banksean@gmail.com> 1745203501 -0700

webui: mv scroll behavior to sketch-timeline

Moves the automatic scrolling behavior from sketch-app-shell into
sketch-timeline, where it makes more sense.

This change also makes automatic scrolling conditional on
an internal "scrollingState", which we update whenever you
manually scroll to, or away from the bottom of the timeline.

If you scroll to the bottom of the timeline, then it's "sticky"
and newly arriving messages will keep scrolling you to the bottom
as they render.

If you scroll up to older messages though, then we stop automatically
scrolling you to the latest messages at the bottom of the timeline.

When the timeline is in this latter "floating" scrollingState, we
also render a floating down-arrow button over the lower right corner
of the timeline.  Clicking on this will take you down to the latest
message at the end of the timeline.