chore: use AddClassHandler instead of OnPropertyChanged.

src/Avalonia/HandyControl_Avalonia/Controls/Other/DashedBorder.cs

@@ -52,6 +52,7 @@ public class DashedBorder : Decorator
             BorderDashThicknessProperty,
             BorderThicknessProperty
         );
+
         AffectsRender<DashedBorder>(
             BorderDashArrayProperty,
             BorderDashCapProperty,
@@ -60,6 +61,26 @@ public class DashedBorder : Decorator
             BorderBrushProperty,
             BackgroundProperty
         );
+
+        BorderThicknessProperty.Changed.AddClassHandler<DashedBorder>(OnClearPenCache);
+        BorderDashThicknessProperty.Changed.AddClassHandler<DashedBorder>(OnClearPenCache);
+        BorderBrushProperty.Changed.AddClassHandler<DashedBorder>(OnClearPenCache);
+        BackgroundProperty.Changed.AddClassHandler<DashedBorder>(OnClearPenCache);
+        BorderDashArrayProperty.Changed.AddClassHandler<DashedBorder>(OnClearPenCache);
+        BorderDashCapProperty.Changed.AddClassHandler<DashedBorder>(OnClearPenCache);
+        BorderDashOffsetProperty.Changed.AddClassHandler<DashedBorder>(OnClearPenCache);
+    }
+
+    private static void OnClearPenCache(AvaloniaObject d, AvaloniaPropertyChangedEventArgs e)
+    {
+        var border = (DashedBorder)d;
+        border._leftPenCache = null;
+        border._rightPenCache = null;
+        border._topPenCache = null;
+        border._bottomPenCache = null;
+        border._geometryPenCache = null;
+        border._backgroundGeometryCache = null;
+        border._borderGeometryCache = null;
     }
 
     public double BorderDashThickness
@@ -145,34 +166,6 @@ public class DashedBorder : Decorator
         _layoutThickness = new Thickness?();
     }
 
-    protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
-    {
-        base.OnPropertyChanged(change);
-
-        string propertyName = change.Property.Name;
-        if (string.Equals(propertyName, nameof(BorderThickness)) ||
-            string.Equals(propertyName, nameof(BorderDashThickness)) ||
-            string.Equals(propertyName, nameof(BorderBrush)) ||
-            string.Equals(propertyName, nameof(Background)) ||
-            string.Equals(propertyName, nameof(BorderDashArray)) ||
-            string.Equals(propertyName, nameof(BorderDashCap)) ||
-            string.Equals(propertyName, nameof(BorderDashOffset)))
-        {
-            ClearCache();
-        }
-    }
-
-    private void ClearCache()
-    {
-        _leftPenCache = null;
-        _rightPenCache = null;
-        _topPenCache = null;
-        _bottomPenCache = null;
-        _geometryPenCache = null;
-        _backgroundGeometryCache = null;
-        _borderGeometryCache = null;
-    }
-
     public override void Render(DrawingContext context)
     {
         var radii = CornerRadius;

src/Avalonia/HandyControl_Avalonia/Controls/Panel/UniformSpacingPanel.cs

@@ -59,6 +59,14 @@ public class UniformSpacingPanel : Panel
             ItemHorizontalAlignmentProperty,
             ItemVerticalAlignmentProperty
         );
+
+        OrientationProperty.Changed.AddClassHandler<UniformSpacingPanel>(OnOrientationChanged);
+    }
+
+    private static void OnOrientationChanged(AvaloniaObject d, AvaloniaPropertyChangedEventArgs e)
+    {
+        var p = (UniformSpacingPanel)d;
+        p._orientation = e.GetNewValue<Orientation>();
     }
 
     public Orientation Orientation
@@ -117,16 +125,6 @@ public class UniformSpacingPanel : Panel
 
     private static double CoerceLength(AvaloniaObject _, double length) => length < 0 ? 0 : length;
 
-    protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
-    {
-        base.OnPropertyChanged(change);
-
-        if (string.Equals(change.Property.Name, nameof(Orientation)))
-        {
-            _orientation = change.GetNewValue<Orientation>();
-        }
-    }
-
     protected override Size MeasureOverride(Size availableSize)
     {
         var curLineSize = new PanelUvSize(_orientation);