Unknown attachable member 'VirtualizingStackPanel.IsVirtualizing' on element 'TreeView'

[y-mk-yc]

I cannot use attached member "VirtualizingStackPanel.IsVirtualizing" not only on 'TreeView', but also some other element such as ' ListBox'. Also ,there's no wavy lines under the code.
I cannot use NodeMouseClick, either.

[marcelwgn]

VirtualizingStackPanel and NodeMouseClick are WPF APIs, WinUI 3 API is based on the UWP APIs and does not support using WPF properties on WinUI 3 controls.