Navigation View | Show confirmation dialog before navigating without updating the UI?

[duongdokms]

Hi everyone, I am using Fluent Avalonia UI with Reactive UI for desktop application.
I have an issue is that when the confirmation dialog is being shown, the navigation view item is already selected (UI already updated) without the user confirmation.

axaml:

<ui:NavigationView Classes="AppNav"
                   PaneDisplayMode="Left"
                   IsSettingsVisible="False"
                   IsPaneToggleButtonVisible="False"
                   OpenPaneLength="256">
	<Interaction.Behaviors>
		<EventTriggerBehavior EventName="SelectionChanged">
			<InvokeCommandAction Command="{Binding AppNavSelectionChangedCommand}"
                                 PassEventArgsToCommand="True" />
		</EventTriggerBehavior>
	</Interaction.Behaviors>
	<ui:NavigationView.MenuItems>
            ... Items in here
	</ui:NavigationView.MenuItems>
</ui:NavigationView>

ViewModel:

public ReactiveCommand<NavigationViewSelectionChangedEventArgs, Unit> AppNavSelectionChangedCommand { get; set; } = null!;
....

pubic Constructor()
{
    AppNavSelectionChangedCommand = ReactiveCommand.CreateFromTask<NavigationViewSelectionChangedEventArgs> 
     (OnAppNavSelectionChanged);
}

....
private async Task OnAppNavSelectionChanged(NavigationViewSelectionChangedEventArgs eventArgs)
{
   // Showing confirmation dialog
   var contentDialog = new ContentDialog
   {
       Title = "Question",
       Content = "Are you sure you want to leave this page?"
       PrimaryButtonText = opts.OkText,
       DefaultButton = ContentDialogButton.Primary
    };

   var result = await contentDialog.ShowAsync(); // <--- Dialog being shown, the UI already updated. How to prevent?
  
   if (result == ContentDialogResult.Primary) { 
      // Only navigate when user click confirm
   } else {
     // Should not navigate
   }
}

Is there any solution for this? Thanks everyone.

[timunie]

SelectionChanged is probably too late.

Idea: Why don't bind to SelectedItem and handle the dialog in the setter?