timeout is now a DP and removed unused method

Author: vgromfeld

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/FocusBehavior/FocusBehaviorPage.xaml.cs

@@ -2,21 +2,15 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
 
 namespace Microsoft.Toolkit.Uwp.SampleApp.SamplePages
 {
     /// <summary>
     /// A page that shows how to use the FocusBehavior
     /// </summary>
-    public sealed partial class FocusBehaviorPage : Page, IXamlRenderListener
+    public sealed partial class FocusBehaviorPage : Page
     {
         public FocusBehaviorPage() => InitializeComponent();
-
-        public void OnXamlRendered(FrameworkElement control)
-        {
-
-        }
     }
 }

Microsoft.Toolkit.Uwp.UI/Behaviors/FocusBehavior.cs

@@ -30,7 +30,16 @@ public sealed class FocusBehavior : BehaviorBase<UIElement>
             typeof(FocusBehavior),
             new PropertyMetadata(null, OnTargetsPropertyChanged));
 
-        private static readonly TimeSpan FocusEngagementTimeout = TimeSpan.FromMilliseconds(100);
+
+        /// <summary>
+        /// The DP to store the <see cref="FocusEngagementTimeout"/> property value.
+        /// </summary>
+        public static readonly DependencyProperty FocusEngagementTimeoutProperty = DependencyProperty.Register(
+            nameof(FocusEngagementTimeout),
+            typeof(TimeSpan),
+            typeof(FocusBehavior),
+            new PropertyMetadata(TimeSpan.FromMilliseconds(100)));
+
         private DispatcherTimer _timer;
 
         /// <summary>
@@ -47,6 +56,16 @@ public FocusTargetList Targets
             set => SetValue(TargetsProperty, value);
         }
 
+        /// <summary>
+        /// Gets or sets the timeout before the <see cref="FocusBehavior"/> stops trying to set the focus to a control with
+        /// a higher priority.
+        /// </summary>
+        public TimeSpan FocusEngagementTimeout
+        {
+            get => (TimeSpan)GetValue(FocusEngagementTimeoutProperty);
+            set => SetValue(FocusEngagementTimeoutProperty, value);
+        }
+
         /// <inheritdoc/>
         protected override void OnAssociatedObjectLoaded() => ApplyFocus();