feat: change animation creation to loaded, thus it works in popup.

src/Ursa/Controls/SelectionList/SelectionList.cs

@@ -19,29 +19,30 @@ public class SelectionList: SelectingItemsControl
     public const string PART_Indicator = "PART_Indicator";
     private static readonly FuncTemplate<Panel?> DefaultPanel = new(() => new StackPanel());
 
-    private ImplicitAnimationCollection? _implicitAnimations;
+    public static readonly StyledProperty<Control?> IndicatorProperty =
-    private ContentPresenter? _indicator;
+        AvaloniaProperty.Register<SelectionList, Control?>(
-
-    public static readonly StyledProperty<Control?> IndicatorProperty = AvaloniaProperty.Register<SelectionList, Control?>(
             nameof(Indicator));
 
-    public Control? Indicator
+    private ImplicitAnimationCollection? _implicitAnimations;
-    {
+    private ContentPresenter? _indicator;
-        get => GetValue(IndicatorProperty);
-        set => SetValue(IndicatorProperty, value);
-    }
 
     static SelectionList()
     {
         SelectionModeProperty.OverrideMetadata<SelectionList>(
             new StyledPropertyMetadata<SelectionMode>(
-            defaultValue: SelectionMode.Single, 
+                SelectionMode.Single,
                 coerce: (_, _) => SelectionMode.Single)
         );
         SelectedItemProperty.Changed.AddClassHandler<SelectionList, object?>((list, args) =>
             list.OnSelectedItemChanged(args));
     }
 
+    public Control? Indicator
+    {
+        get => GetValue(IndicatorProperty);
+        set => SetValue(IndicatorProperty, value);
+    }
+
     private void OnSelectedItemChanged(AvaloniaPropertyChangedEventArgs<object?> args)
     {
         var newValue = args.NewValue.Value;
@@ -50,12 +51,14 @@ public class SelectionList: SelectingItemsControl
             OpacityProperty.SetValue(0d, _indicator);
             return;
         }
+
         var container = ContainerFromItem(newValue);
         if (container is null)
         {
             OpacityProperty.SetValue(0d, _indicator);
             return;
         }
+
         OpacityProperty.SetValue(1d, _indicator);
         InvalidateMeasure();
         // InvalidateArrange();
@@ -69,10 +72,7 @@ public class SelectionList: SelectingItemsControl
             var container = ContainerFromItem(SelectedItem);
             if (container is null) return size;
             var bounds = container.Bounds;
-            if (ItemsPanelRoot?.Bounds.Position is { } p)
+            if (ItemsPanelRoot?.Bounds.Position is { } p) bounds = bounds.Translate(p);
-            {
-                bounds = bounds.Translate(p);
-            }
             _indicator.Arrange(bounds);
         }
         else
@@ -80,6 +80,7 @@ public class SelectionList: SelectingItemsControl
             // This is a hack. The indicator is not visible, so we arrange it to a 1x1 rectangle
             _indicator?.Arrange(new Rect(new Point(), new Size(1, 1)));
         }
+
         return size;
     }
 
@@ -97,22 +98,19 @@ public class SelectionList: SelectingItemsControl
     {
         base.OnApplyTemplate(e);
         _indicator = e.NameScope.Find<ContentPresenter>(PART_Indicator);
-        EnsureIndicatorAnimation();
     }
 
     protected override void OnLoaded(RoutedEventArgs e)
     {
         base.OnLoaded(e);
+        EnsureIndicatorAnimation();
         if (_indicator is not null && SelectedItem is not null)
         {
             var container = ContainerFromItem(SelectedItem);
             if (container is null) return;
             _indicator.Opacity = 1;
             var bounds = container.Bounds;
-            if (ItemsPanelRoot?.Bounds.Position is { } p)
+            if (ItemsPanelRoot?.Bounds.Position is { } p) bounds = bounds.Translate(p);
-            {
-                bounds = bounds.Translate(p);
-            }
             _indicator.Arrange(bounds);
         }
     }
@@ -123,10 +121,7 @@ public class SelectionList: SelectingItemsControl
         {
             _indicator.Opacity = 0;
             SetUpAnimation();
-            if (ElementComposition.GetElementVisual(_indicator) is { } v)
+            if (ElementComposition.GetElementVisual(_indicator) is { } v) v.ImplicitAnimations = _implicitAnimations;
-            {
-                v.ImplicitAnimations = _implicitAnimations;
-            }
         }
     }
 
@@ -167,9 +162,7 @@ public class SelectionList: SelectingItemsControl
         var hotkeys = Application.Current!.PlatformSettings?.HotkeyConfiguration;
 
         if (e.Key.ToNavigationDirection() is { } direction && direction.IsDirectional())
-        {
             e.Handled |= MoveSelection(direction, WrapSelection);
-        }
         base.OnKeyDown(e);
     }
 }