ItemsRepeater behaves erratically when adding items to front of list

[mike-ward]

https://github.com/mike-ward/demoscroll

DemoScroll is a minimal Avalonia desktop application that demonstrates undesirable scrolling behavior.

What it does:

• Constructs a window that contains an ItemsRepeater
• Fills a list with sample text that is bound to the ItemsRepeater.
• Starts a 2 second timer and inserts sample text to the front of the list.

What it demonstrates:

• Text will start disappearing the moment new text is added by the timer.
• Grab the scrollbar thumb and move up and down. Application will stop drawing and otherwise behave erratically.

Desktop (please complete the following information):

• OS: Microsoft Windows [Version 10.0.19042.746]
• Version 0.10

Additional context
Related to AvaloniaUI/Avalonia#5151

[mike-ward]

#2 may also be related.

[grokys]

I'm guessing that we need to port microsoft/microsoft-ui-xaml#3699 to fix this.

[maxkatz6]

@grokys is was already ported
AvaloniaUI/Avalonia#5203