This is a sub-menu in Settings > Timeline that was added in version 23.09 with the following options:
- Center the Playhead - you can still move the playhead before the center point. But during playback, when the playhead reaches the center, it stops moving and the timeline starts scrolling in a smooth fashion.
- No - no automatically scrolling
- Page - when the playhead reaches the end of the timeline panel, the timeline suddenly scrolls by nearly the width of the timeline panel and stops scrolling until the playhead reaches the end again. This seems to be the most common among video editing tools - except perhaps by the page size.
- Smooth - the traditional behavior of Shotcut: when the playhead reaches the end of the timeline panel, it remains there and the timeline starts scrolling smoothly.
Scroll to Playhead on Zoom is a checkbox separate from the above options. This controls whether Shotcut scrolls the timeline to keep the playhead within view after changing the timeline level of zoom.