[NPE][Canary][Prod] Scrolling- When scrolling back to the top, the entire TreeView structure in 'Content' section collapses automatically.

[sakshi173]

Current behavior

System.Drawing.Common.8.0.4._.NuGet.Package.Explorer.-.Google.Chrome.2024-04-12.09-42-51.mp4

Uno.Templates.5.1.25._.NuGet.Package.Explorer.-.Google.Chrome.2024-04-12.09-45-27.mp4

Expected behavior

The tree structure should not collapse.

How to reproduce it (as minimally and precisely as possible)

1. Open NPE https://purple-pond-0688d230f.azurestaticapps.net/ or https://nuget.info/
2. Click on 'Open' button and go for any .Net file(the file for which the tree view structure depth is more) like for Uno. Templates
3. Go to 'Content' section.
4. Click on multiple folders to open.
5. Notice that when scrolling back to the top, the entire Tree View structure in 'Content' section collapses automatically.

Workaround

No response

Works on UWP/WinUI

None

Environment

No response

NuGet package version(s)

No response

Affected platforms

WebAssembly

IDE

No response

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

No response

[jeromelaban]

@Youssef1313 could you take a look?

[Youssef1313]

@jeromelaban Debugging on Skia as it's better debugging experience there, it looks like parts of the UI are created on a background thread, causing DispatcherQueue to be null (see here and here). This then causes null ref exceptions down the road. But even after avoiding this, the problem still remains. Continuing investigation.

[ramezgerges]

Fixing in #16303, Submitted to WinUI in microsoft/microsoft-ui-xaml#9549