Merge pull request #333 from higankanshi/master

Fix Ripple can't reset in Popup control.

Author: ButchersBoy

MaterialDesignThemes.Wpf/Ripple.cs

@@ -3,6 +3,7 @@
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Controls.Primitives;
 using System.Windows.Input;
 using System.Windows.Media;
 using System.Windows.Media.Animation;
@@ -26,6 +27,8 @@ static Ripple()
 
             EventManager.RegisterClassHandler(typeof(Window), Mouse.PreviewMouseUpEvent, new MouseButtonEventHandler(MouseButtonEventHandler), true);
             EventManager.RegisterClassHandler(typeof (Window), Mouse.MouseMoveEvent, new MouseEventHandler(MouseMouveEventHandler), true);
+            EventManager.RegisterClassHandler(typeof(Popup), Mouse.PreviewMouseUpEvent, new MouseButtonEventHandler(MouseButtonEventHandler), true);
+            EventManager.RegisterClassHandler(typeof(Popup), Mouse.MouseMoveEvent, new MouseEventHandler(MouseMouveEventHandler), true);
         }
 
         public Ripple()