Long text scrolling jitter #140

There is an issue with scroll behavior in your implementation.
If you quickly scroll a long text with the mouse wheel, it awkwardly glitches with a setback jittering. Tried both chrome and ff.

I investigated this and prepared a patch for the scroll jitter.

Repro steps

1. Open AceDiff with long content on both sides.
2. Enable scroll sync (lockScrolling: true).
3. Quickly scroll with mouse wheel in either pane.
4. Observe occasional backward/setback jumps (jitter).

Expected

Smooth synchronized scrolling without rollback/jumps.

Actual

When scrolling fast, panes sometimes "fight" each other and produce setback jitter.

Suspected cause

Both panes have independent throttled changeScrollTop handlers.
Under fast wheel input, delayed/throttled callbacks can execute out of order and compete.

Proposed fix

Use one centralized scroll scheduler:

• keep lastScrollSource
• cancel pending frame
• sync once per requestAnimationFrame
  This removes throttle competition between left/right handlers.

I attached a patch file:
issue-140-scroll-jitter.patch
(contains changes in src/index.ts)

issue-140-scroll-jitter.patch