Fixed highlightcolor of layers manager drop

src/PixiEditor.AvaloniaUI/Views/Layers/LayersManager.axaml.cs

@@ -22,7 +22,10 @@ internal partial class LayersManager : UserControl
     {
         InitializeComponent();
         numberInput.OnScrollAction = () => NumberInput_LostFocus(null, null);
-        highlightColor = (Brush?)App.Current.Resources["SoftSelectedLayerColor"];
+        if (App.Current.TryGetResource("SoftSelectedLayerBrush", App.Current.ActualThemeVariant, out var value))
+        {
+            highlightColor = value as IBrush;
+        }
     }
 
     private void LayerControl_MouseDown(object sender, PointerPressedEventArgs e)