TabControl seemingly does not maintain per-tab scroll position

[PathogenDavid]

Environment

Observed with XamlControlsGallery (with a slightly modified version to use the latest Avalonia CI build.)

Windows 10 2004

Steps to reproduce

1. Launch the app
2. Go to the Date and Time page
3. Scroll down to the bottom
4. Switch to the Layout page

Expected behavior

The page starts out at the top

(This is the behavior if you go straight to the Layout page.)

Actual behavior

The page is already scrolled down slightly

[PathogenDavid]

Consider fixing #4759 before this one because this bug (probably) makes it easier to reproduce.

[Gillibald]

https://github.com/AvaloniaUI/XamlControlsGallery/blob/29548cf16f518d03472bf96f5a60f9ceadc01074/XamlControlsGallery/Styles/SideBar.xaml#L36

This has nothing to do with the TabControl directly. This is more of an issue withe the custom template. The TabControl'S content is wrapped inside a ScrollViewer and that is shared by all tabs. So to get your desired behavior the ContentTemplate needs to use a ScrollViewer instead.

[PathogenDavid]

Ah, I actually looked for that in the DevTools window but I guess I missed it. This issue should probably be move to the XamlControlsGallery repo then.