fixes

Toolkit.Foundation/ComponentConfigurationViewModel.cs

@@ -51,10 +51,10 @@ public partial class ComponentConfigurationViewModel<TConfiguration, TValue, TAc
     [ObservableProperty]
     private object description = description;
 
-    public override Task Activated()
+    public override Task OnActivated()
     {
         Value = valueDelegate.Invoke(configuration);
-        return base.Activated();
+        return base.OnActivated();
     }
 
     public Task Handle(ChangedEventArgs<TConfiguration> args)
@@ -93,10 +93,10 @@ public partial class ComponentConfigurationViewModel<TConfiguration, TValue, TDe
     [ObservableProperty]
     private TDescription description = description;
 
-    public override Task Activated()
+    public override Task OnActivated()
     {
         Value = valueDelegate.Invoke(configuration);
-        return base.Activated();
+        return base.OnActivated();
     }
 
     public Task Handle(ChangedEventArgs<TConfiguration> args)

Toolkit.Foundation/IActivated.cs

@@ -2,5 +2,5 @@
 
 public interface IActivated
 {
-    Task Activated();
+    Task OnActivated();
 }

Toolkit.Foundation/IDeactivated.cs

@@ -2,5 +2,5 @@
 
 public interface IDeactivated
 {
-    Task Deactivated();
+    Task OnDeactivated();
 }

Toolkit.Foundation/IDeactivating.cs

@@ -2,5 +2,5 @@
 
 public interface IDeactivating
 {
-    Task Deactivating();
+    Task OnDeactivating();
 }

Toolkit.Foundation/Observable.cs

@@ -24,6 +24,9 @@ public partial class Observable(IServiceProvider provider,
 {
     private readonly Dictionary<string, object> trackedProperties = [];
 
+    [ObservableProperty]
+    private bool isActivated;
+
     [ObservableProperty]
     private bool isActive;
 
@@ -42,6 +45,12 @@ public partial class Observable(IServiceProvider provider,
 
     public ISubscriber Subscriber { get; } = subscriber;
 
+    public virtual Task OnActivated()
+    {
+        IsActivated = true;
+        return Task.CompletedTask;
+    }
+
     public void Commit()
     {
         foreach (object trackedProperty in trackedProperties.Values)
@@ -50,6 +59,15 @@ public partial class Observable(IServiceProvider provider,
         }
     }
 
+    public virtual Task OnDeactivated()
+    {
+        IsActivated = false;
+        return Task.CompletedTask;
+    }
+
+    public virtual Task OnDeactivating() =>
+        Task.CompletedTask;
+
     public virtual void Dispose()
     {
         GC.SuppressFinalize(this);
@@ -67,25 +85,6 @@ public partial class Observable(IServiceProvider provider,
         Subscriber.Subscribe(this);
     }
 
-    [ObservableProperty]
-    private bool isActivated;
-
-    public virtual Task Activated()
-    {
-        IsActivated = true;
-        return Task.CompletedTask;
-    }
-
-
-    public virtual Task Deactivated()
-    {
-        IsActivated = false;
-        return Task.CompletedTask;
-    }
-
-    public virtual Task Deactivating() =>
-        Task.CompletedTask;
-
     public void Revert()
     {
         foreach (object trackedProperty in trackedProperties.Values)

Toolkit.Foundation/ObservableCollection.cs

@@ -127,7 +127,7 @@ public partial class ObservableCollection<TItem> :
 
     object? IList.this[int index]
     {
-        get => collection[index];
+        get => index >= 0 ? collection[index] : null;
         set
         {
             TItem? item = default;
@@ -144,7 +144,7 @@ public partial class ObservableCollection<TItem> :
         }
     }
 
-    public virtual Task Activated()
+    public virtual Task OnActivated()
     {
         IsActivated = true;
         while (pendingEvents.Count > 0)
@@ -251,13 +251,13 @@ public partial class ObservableCollection<TItem> :
     void ICollection.CopyTo(Array array, int index) =>
         collection.CopyTo((TItem[])array, index);
 
-    public virtual Task Deactivated()
+    public virtual Task OnDeactivated()
     {
         IsActivated = false;
         return Task.CompletedTask;
     }
 
-    public virtual Task Deactivating() =>
+    public virtual Task OnDeactivating() =>
         Task.CompletedTask;
 
     public virtual void Dispose()
@@ -642,11 +642,15 @@ public partial class ObservableCollection<TItem> :
             }
         }
     }
+
     partial void OnSelectedItemChanged(TItem? oldValue, TItem? newValue)
     {
         if (oldValue is ISelectable oldSelection)
         {
-            oldSelection.IsSelected = false;
+            if (oldSelection.IsSelected)
+            {
+                oldSelection.IsSelected = false;
+            }
         }
 
         if (newValue is ISelectable newSelection)