OnNavigatedFrom support

src/Wpf.Ui/Controls/Navigation/NavigationViewContentPresenter.cs

@@ -77,6 +77,11 @@ protected override void OnInitialized(EventArgs e)
                 return;
 
             NotifyContentAboutNavigatingTo(eventArgs.Content);
+
+            if (eventArgs.Navigator is not NavigationViewContentPresenter navigator)
+                return;
+
+            NotifyContentAboutNavigatingFrom(navigator.Content);
         };
 
         Navigated += static (sender, eventArgs) =>
@@ -88,6 +93,14 @@ protected override void OnInitialized(EventArgs e)
 
             self.ApplyTransitionEffectToNavigatedPage(eventArgs.Content);
         };
+
+        Unloaded += (sender, _) =>
+        {
+            if (sender is NavigationViewContentPresenter navigator)
+            {
+                NotifyContentAboutNavigatingFrom(navigator.Content);
+            }
+        };
     }
 
     protected override void OnMouseDown(MouseButtonEventArgs e)
@@ -112,6 +125,18 @@ private static void NotifyContentAboutNavigatingTo(object content)
             navigationAwareCurrentContent.OnNavigatedTo();
     }
 
+    private static void NotifyContentAboutNavigatingFrom(object content)
+    {
+        if (content is INavigationAware navigationAwareNavigationContent)
+            navigationAwareNavigationContent.OnNavigatedFrom();
+
+        if (content is INavigableView<object> { ViewModel: INavigationAware navigationAwareNavigableViewViewModel })
+            navigationAwareNavigableViewViewModel.OnNavigatedFrom();
+
+        if (content is FrameworkElement { DataContext: INavigationAware navigationAwareCurrentContent })
+            navigationAwareCurrentContent.OnNavigatedFrom();
+    }
+
     private void ApplyTransitionEffectToNavigatedPage(object content)
     {
         if (TransitionDuration < 1)