add ShowEmpty prop for Empty control

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

@@ -1,5 +1,6 @@
 using System.Windows;
 using System.Windows.Controls;
+using HandyControl.Data;
 
 namespace HandyControl.Controls
 {
@@ -22,5 +23,14 @@ namespace HandyControl.Controls
             get => GetValue(LogoProperty);
             set => SetValue(LogoProperty, value);
         }
+
+        public static readonly DependencyProperty ShowEmptyProperty = DependencyProperty.RegisterAttached(
+            "ShowEmpty", typeof(bool), typeof(Empty), new FrameworkPropertyMetadata(ValueBoxes.FalseBox, FrameworkPropertyMetadataOptions.Inherits));
+
+        public static void SetShowEmpty(DependencyObject element, bool value)
+            => element.SetValue(ShowEmptyProperty, value);
+
+        public static bool GetShowEmpty(DependencyObject element)
+            => (bool) element.GetValue(ShowEmptyProperty);
     }
 }