UI Freeze and doesn't repaint when using scroll bars on Linux

I'm using HtmlRenderer.Mono to render HTML via Mono .Net Framework 4.7.1 Winforms.

I've written a small demo app which works fine - it's a simple htmlPanel with event subscriptions for loading/caching images - works great.

When I integrate this demo form into an existing larger app, scrolling freezes the UI the the whole app. There's no crash log or output in console....it's as though something crashes the UI thread, The app is still running, as I can see it's process via top and monitor it's CPU load.

The crash isn't instant either. I can slide the scroller up and down for between 2 and 20 seconds.....at some point it locks.

HtmlRenderer.Mono source code doesn't appear to be anywhere so I can't debug it.

Can anyone help?

Thanks!

使用小型示範應用程式和較大的整合應用程式作為重現的起點；透過滾動最多 20 秒來重現 Linux/Mono WinForms 凍結，並擷取診斷輸出。此 issue 未指定原始檔案或測試，因此完成這項工作需要一個最小可重現案例，或驗證滾動不再凍結或停止重繪。

由索引模型根據 Issue 內容生成。