Close menu when clicked outside.

Perspex.Controls/Menu.cs

@@ -6,14 +6,19 @@
 
 namespace Perspex.Controls
 {
+    using System;
     using System.Linq;
+    using Perspex.Input;
     using Perspex.LogicalTree;
+    using Perspex.Rendering;
 
     public class Menu : ItemsControl, IMenu
     {
         private static readonly ItemsPanelTemplate DefaultPanel =
             new ItemsPanelTemplate(() => new StackPanel { Orientation = Orientation.Horizontal });
 
+        private IDisposable subscription;
+
         static Menu()
         {
             ItemsPanelProperty.OverrideDefaultValue(typeof(Menu), DefaultPanel);
@@ -31,5 +36,30 @@ namespace Perspex.Controls
                 }
             }
         }
+
+        protected override void OnAttachedToVisualTree(IRenderRoot root)
+        {
+            base.OnAttachedToVisualTree(root);
+
+            var r = root as IInputElement;
+            this.subscription = r.AddHandler(
+                InputElement.PointerPressedEvent, 
+                this.RootPointerPressed, 
+                Interactivity.RoutingStrategies.Tunnel);
+        }
+
+        protected override void OnDetachedFromVisualTree(IRenderRoot oldRoot)
+        {
+            base.OnDetachedFromVisualTree(oldRoot);
+            this.subscription.Dispose();
+        }
+
+        private void RootPointerPressed(object sender, PointerPressEventArgs e)
+        {
+            foreach (var i in this.GetLogicalChildren().Cast<MenuItem>())
+            {
+                i.IsSubMenuOpen = false;
+            }
+        }
     }
 }

Perspex.Controls/MenuItem.cs

@@ -6,10 +6,15 @@
 
 namespace Perspex.Controls
 {
+    using System;
+    using System.Linq;
+    using System.Windows.Input;
     using Perspex.Controls.Primitives;
     using Perspex.Input;
     using Perspex.LogicalTree;
-    using System.Windows.Input;
+    using Perspex.Collections;
+    using Perspex.Rendering;
+    using Perspex.Controls.Templates;
 
     public class MenuItem : HeaderedItemsControl
     {
@@ -25,6 +30,11 @@ namespace Perspex.Controls
         public static readonly PerspexProperty<bool> IsSubMenuOpenProperty =
             PerspexProperty.Register<MenuItem, bool>("IsSubMenuOpen");
 
+        static MenuItem()
+        {
+            IsSubMenuOpenProperty.Changed.Subscribe(SubMenuOpenChanged);
+        }
+
         public ICommand Command
         {
             get { return this.GetValue(CommandProperty); }
@@ -64,5 +74,26 @@ namespace Perspex.Controls
                 this.IsSubMenuOpen = !this.IsSubMenuOpen;
             }
         }
+
+        private void OnSubMenuOpenChanged(bool open)
+        {
+            if (!open && this.Items != null)
+            {
+                foreach (var item in this.Items.Cast<object>().OfType<MenuItem>())
+                {
+                    item.IsSubMenuOpen = false;
+                }
+            }
+        }
+
+        private static void SubMenuOpenChanged(PerspexPropertyChangedEventArgs e)
+        {
+            var sender = e.Sender as MenuItem;
+
+            if (sender != null)
+            {
+                sender.OnSubMenuOpenChanged((bool)e.NewValue);
+            }
+        }
     }
 }