Enhance data binding and simplify activation logic

- Updated `ListBox` in `ConductorView.axaml` to bind
  `SelectedItem` to `ActiveItem` for two-way data binding.
- Removed `OnActivateAsync` method in `ConductorViewModel.cs`
  to simplify the activation process.
- Adjusted `Loaded` event handling in `ActionMessage.cs`
  for improved clarity.
- Added convention in `ConventionManager.cs` to bind
  `ItemsSource` of `ListBox` to `DataContext`.
- Changed `Unloaded` event handler in `View.cs` to use
  `RoutedEventArgs` for proper cleanup in Avalon.

Author: vb2ae

samples/features/Features.Avalonia/Views/ConductorView.axaml

@@ -18,7 +18,7 @@
         </StackPanel>
 
 
-        <ListBox Name="Items" Grid.Row="1" Margin="40,0">
+        <ListBox Name="Items" Grid.Row="1" Margin="40,0" SelectedItem="{Binding ActiveItem, Mode=TwoWay}">
             <ListBox.ItemsPanel>
                 <ItemsPanelTemplate>
                     <VirtualizingStackPanel Orientation="Horizontal"/>

samples/features/Features.CrossPlatform.Shared/ViewModels/ConductorViewModel.cs

@@ -13,11 +13,6 @@ public ConductorViewModel()
             Items.CollectionChanged += (s, e) => NotifyOfPropertyChange(() => CanCloseTab);
         }
 
-        protected override async Task OnActivateAsync(CancellationToken cancellationToken)
-        {
-            // Optionally perform any logic before activation here
-            await base.OnActivateAsync(cancellationToken);
-        }
         protected override async Task OnActivatedAsync(CancellationToken cancellationToken)
         {
             // Optionally perform any logic after activation here

src/Caliburn.Micro.Platform/ActionMessage.cs

@@ -214,7 +214,6 @@ protected override void OnAttached()
                 if (View.ExecuteOnLoad(AssociatedObject, ElementLoaded))
                 {
 #if AVALONIA
-                    //string eventName = "AttachedToLogicalTree";
                     string eventName = "Loaded";
                     var trigger = Interaction.GetBehaviors(AssociatedObject)
                         .OfType<EventTrigger>()

src/Caliburn.Micro.Platform/ConventionManager.cs

@@ -340,6 +340,7 @@ static ConventionManager()
 #endif
 #if AVALONIA
             AddElementConvention<UserControl>(UserControl.IsVisibleProperty, "DataContext", loadedEvent);
+            AddElementConvention<ListBox>(ListBox.ItemsSourceProperty, "DataContext", loadedEvent);
 #else
             AddElementConvention<UserControl>(UserControl.VisibilityProperty, "DataContext", loadedEvent);
 #endif

src/Caliburn.Micro.Platform/View.cs

@@ -234,13 +234,13 @@ public static bool ExecuteOnLoad(FrameworkElement element, RoutedEventHandler ha
 #if AVALONIA
         public static void ExecuteOnUnload(FrameworkElement element, EventHandler handler)
         {
-            EventHandler<LogicalTreeAttachmentEventArgs> unloaded = null;
+            EventHandler<RoutedEventArgs> unloaded = null;
             unloaded = (s, e) =>
             {
-                element.DetachedFromLogicalTree -= unloaded;
+                element.Unloaded -= unloaded;
                 handler(s, e);
             };
-            element.DetachedFromLogicalTree += unloaded;
+            element.Unloaded += unloaded;
         }
 #else
         public static void ExecuteOnUnload(FrameworkElement element, RoutedEventHandler handler)