Prevent or cancel navigation?

[gleclair]

First off, many thanks to @pomianowski and other contributors for creating and maintaining this solution, your work is very much appreciated!!
My question is: Is there a way for a view model to disable or cancel navigation? If a user is in the middle of editing, I want them to either save or discard changes before moving to another screen. Maybe I could disable the navigation menu when editing starts, or wire into an event to cancel it? Hopefully I'm missing something easy, any suggestions are appreciated.

[gleclair]

I was able to use CommunityToolKit.MVVM.Messaging so each viewmodel can send a message to the MainWindowViewModel when it's busy and wants to block navigation. MainWindowViewModel will then set its CanNavigate property to false. My MainWindow code behind wires to the RootNavigation_Navigating event:
private void RootNavigation_Navigating(NavigationView sender, NavigatingCancelEventArgs args) { if(!ViewModel.CanNavigate) args.Cancel = true; }
This solution works alright, but there's a few issues:

1. There's no visual indication that navigation is not currently allowed.
2. The navigation seems to only be partially cancelled, for example the view model for the requested page is actually constructed.

Has anyone got a suggestion to improve this? Thanks!