The ruler scrub set the time under the pointer and never moved the visible span, so with
the timeline zoomed in a scrub couldn't go past the edge, and a preview ran the CTI out of
view. As in After Effects:
- zoomed in, a scrub held past either end of the ruler scrolls the timeline that way,
faster the further past, with the CTI riding the edge (repainting while held);
- during playback, when the CTI leaves the visible span the view pages to start at it
(not past the comp's end).
Tests: a unit test of the paging and edge speed, and a kittest that holds a scrub past the
right end (the view scrolls, the CTI stays at the edge), then past the left end, then plays
from beyond the view (it pages to the CTI). (#468's Shift+F and black-layer items need
more information and aren't part of this.)
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QiAJeFttZp83Fh7YuzAR5f