Issue 2617

[AndreiGorelov]

Issues

Fixes #2617

Proposed changes

• AlphaTabRenderSurface — store render placeholders in a CopyOnWriteArrayList instead of ArrayList, so iterating during onLayout / updates cannot throw ConcurrentModificationException when partials are added or cleared during layout (e.g. rotation, scroll, resize).
• EnvironmentPartials (Android) — run the coroutine scope used by throttle() on Dispatchers.Main instead of Dispatchers.Default, so throttled resize work runs on the UI thread and avoids concurrent use of layout/bounds data from a background dispatcher (related ConcurrentModificationException seen around BoundsLookup during resize).

Checklist

• I consent that this change becomes part of alphaTab under it's current or any future open source license
• Changes are implemented
• New tests were added

No new automated tests: failures depend on Android layout timing and real-device interactions (rotation, scrolling). Verified manually on real devices.

Further details

• This is a breaking change
• This change will require update of the documentation/website