Change type of OpenedEvent and ClosedEvent to RoutedEventHandler (#3090) (#3091)

Co-authored-by: Oliver Ehrenmüller <[email protected]>

Author: greuelpirat

MaterialDesignThemes.Wpf/PopupBox.cs

@@ -381,7 +381,7 @@ protected virtual void OnToggleCheckedContentClick()
             EventManager.RegisterRoutedEvent(
                 "Opened",
                 RoutingStrategy.Bubble,
-                typeof(EventHandler),
+                typeof(RoutedEventHandler),
                 typeof(PopupBox));
 
         /// <summary>
@@ -406,7 +406,7 @@ protected virtual void OnOpened()
             EventManager.RegisterRoutedEvent(
                 "Closed",
                 RoutingStrategy.Bubble,
-                typeof(EventHandler),
+                typeof(RoutedEventHandler),
                 typeof(PopupBox));
 
         /// <summary>
@@ -797,4 +797,4 @@ private static object CoerceToolTipIsEnabled(DependencyObject dependencyObject,
             return popupBox.IsPopupOpen ? false : value;
         }
     }
-}
+}