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!

Use the small demo app and the larger integrated app as reproduction starting points; reproduce the Linux/Mono WinForms freeze by scrolling for up to 20 seconds and capture diagnostic output. The issue names no source file or test, so completion would require a minimal reproducible case or verification that scrolling no longer freezes or stops repainting.

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