更新

WPFDark/StandardControls/ExpanderEventHandler.cs

@@ -0,0 +1,32 @@
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Input;
+
+using WPFDark.Internals;
+
+namespace WPFDark.StandardControls
+{
+    public partial class ExpanderEventHandler
+    {
+        private void OnPreviewMouseWheel(object sender, MouseWheelEventArgs e)
+        {
+            e.Handled = true;
+
+            var e2 = new MouseWheelEventArgs(e.MouseDevice, e.Timestamp, e.Delta)
+            {
+                RoutedEvent = UIElement.MouseWheelEvent
+            };
+
+            (sender as UIElement)?.RaiseEvent(e2);
+        }
+
+        private void Frame_OnLoaded(object sender, RoutedEventArgs e)
+        {
+            var c = (StackPanel) sender;
+            var expander = c.GetParent<Expander>();
+
+            if (expander != null)
+                c.Tag = expander.IsExpanded ? 1.0 : 0.0;
+        }
+    }
+}