tidy the codes

src/Shared/HandyControl_Shared/Controls/Other/Poptip.cs

@@ -0,0 +1,18 @@
+using System.Windows;
+using System.Windows.Controls;
+using HandyControl.Data;
+
+namespace HandyControl.Controls
+{
+    public class Poptip : Control
+    {
+        public static readonly DependencyProperty PlacementProperty = DependencyProperty.Register(
+            "Placement", typeof(TipPlacement), typeof(Poptip), new PropertyMetadata(TipPlacement.Top));
+
+        public TipPlacement Placement
+        {
+            get => (TipPlacement) GetValue(PlacementProperty);
+            set => SetValue(PlacementProperty, value);
+        }
+    }
+}