Improved tab focus handling a bit.

Perspex.Application/Application.cs

@@ -31,8 +31,6 @@ namespace Perspex
 
             Current = this;
             this.Styles = theme;
-            this.FocusManager = new FocusManager();
-            this.InputManager = new InputManager();
             this.RegisterServices();
         }
 
@@ -72,6 +70,12 @@ namespace Perspex
             private set;
         }
 
+        public KeyboardNavigation KeyboardNavigation
+        {
+            get;
+            private set;
+        }
+
         public Styles Styles
         {
             get;
@@ -87,10 +91,15 @@ namespace Perspex
 
         protected virtual void RegisterServices()
         {
+            this.FocusManager = new FocusManager();
+            this.InputManager = new InputManager();
+            this.KeyboardNavigation = new KeyboardNavigation();
+
             Locator.CurrentMutable.Register(() => this, typeof(IGlobalDataTemplates));
             Locator.CurrentMutable.Register(() => this, typeof(IGlobalStyles));
             Locator.CurrentMutable.Register(() => this.FocusManager, typeof(IFocusManager));
             Locator.CurrentMutable.Register(() => this.InputManager, typeof(IInputManager));
+            Locator.CurrentMutable.Register(() => this.KeyboardNavigation, typeof(IKeyboardNavigation));
             Locator.CurrentMutable.Register(() => this.styler, typeof(IStyler));
 
             Locator.CurrentMutable.Register(() => new LayoutManager(), typeof(ILayoutManager));

Perspex.Controls/Primitives/TabStrip.cs

@@ -21,6 +21,7 @@ namespace Perspex.Controls.Primitives
 
         static TabStrip()
         {
+            FocusableProperty.OverrideDefaultValue(typeof(TabStrip), false);
             ItemsPanelProperty.OverrideDefaultValue(typeof(TabStrip), PanelTemplate);
         }
 

Perspex.Controls/TabControl.cs

@@ -26,6 +26,11 @@ namespace Perspex.Controls
         private PerspexReadOnlyListView<ILogical> logicalChildren = 
             new PerspexReadOnlyListView<ILogical>();
 
+        static TabControl()
+        {
+            FocusableProperty.OverrideDefaultValue(typeof(TabControl), false);
+        }
+
         public TabControl()
         {
             this.GetObservable(SelectedItemProperty).Subscribe(x =>

Perspex.Controls/TextBox.cs

@@ -134,6 +134,7 @@ namespace Perspex.Controls
             int caretIndex = this.CaretIndex;
             bool movement = false;
             bool textEntered = false;
+            bool handled = true;
             var modifiers = e.Device.Modifiers;
 
             switch (e.Key)
@@ -213,6 +214,7 @@ namespace Perspex.Controls
                     else
                     {
                         base.OnKeyDown(e);
+                        handled = false;
                     }
 
                     break;
@@ -240,7 +242,10 @@ namespace Perspex.Controls
                 this.SelectionStart = this.SelectionEnd = this.CaretIndex;
             }
 
-            e.Handled = true;
+            if (handled)
+            {
+                e.Handled = true;
+            }
         }
 
         protected override void OnPointerPressed(PointerPressEventArgs e)

Perspex.Input/IKeyboardNavigation.cs

@@ -0,0 +1,15 @@
+// -----------------------------------------------------------------------
+// <copyright file="IKeyboardDevice.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Input
+{
+    public interface IKeyboardNavigation
+    {
+        bool MoveNext(IInputElement element);
+
+        bool MovePrevious(IInputElement element);
+    }
+}

Perspex.Input/InputElement.cs

@@ -221,11 +221,17 @@ namespace Perspex.Input
 
                 if ((modifiers & ModifierKeys.Shift) == 0)
                 {
-                    KeyboardNavigation.MoveNext(this);
+                    if (KeyboardNavigation.Instance.MoveNext(this))
+                    {
+                        e.Handled = true;
+                    }
                 }
                 else
                 {
-                    KeyboardNavigation.MovePrevious(this);
+                    if (KeyboardNavigation.Instance.MovePrevious(this))
+                    {
+                        e.Handled = true;
+                    }
                 }
             }
         }

Perspex.Input/KeyboardNavigation.cs

@@ -8,42 +8,79 @@ namespace Perspex.Input
 {
     using System.Linq;
     using Perspex.VisualTree;
+    using Splat;
 
-    /// <summary>
-    /// TODO: This class is a temporary stop-gap just to add tab handling. Should be replaced 
-    /// with something better thought out and testable etc.
-    /// </summary>
-    public static class KeyboardNavigation
+    public class KeyboardNavigation : IKeyboardNavigation
     {
-        public static void MoveNext(IInputElement element)
+        public static IKeyboardNavigation Instance
         {
-            var siblings = element.GetVisualSiblings().OfType<IInputElement>()
-                .Where(x => x.Focusable)
-                .SkipWhile(x => x != element)
-                .Skip(1);
+            get { return Locator.Current.GetService<IKeyboardNavigation>(); }
+        }
 
-            var next = siblings.FirstOrDefault();
+        public bool MoveNext(IInputElement element)
+        {
+            var parent = element.GetVisualParent();
+            var descendent = element.GetVisualDescendents()
+                .OfType<IInputElement>()
+                .Where(x => x.Focusable && x.IsEnabledCore)
+                .FirstOrDefault();
 
-            if (next != null)
+            if (descendent != null)
+            {
+                FocusManager.Instance.Focus(descendent, true);
+                return true;
+            }
+            else if (parent != null)
             {
-                FocusManager.Instance.Focus(next, true);
+                var sibling = parent.GetVisualChildren()
+                    .OfType<IInputElement>()
+                    .Where(x => x.Focusable && x.IsEnabledCore)
+                    .SkipWhile(x => x != element)
+                    .Skip(1)
+                    .FirstOrDefault();
+
+                if (sibling != null)
+                {
+                    FocusManager.Instance.Focus(sibling, true);
+                    return true;
+                }
             }
+
+            return false;
         }
 
-        public static void MovePrevious(IInputElement element)
+        public bool MovePrevious(IInputElement element)
         {
-            var siblings = element.GetVisualSiblings().OfType<IInputElement>()
-                .Where(x => x.Focusable)
+            var parent = element.GetVisualParent();
+            var descendent = element.GetVisualDescendents()
+                .OfType<IInputElement>()
+                .Where(x => x.Focusable && x.IsEnabledCore)
                 .Reverse()
-                .SkipWhile(x => x != element)
-                .Skip(1);
+                .FirstOrDefault();
 
-            var next = siblings.FirstOrDefault();
-
-            if (next != null)
+            if (descendent != null)
             {
-                FocusManager.Instance.Focus(next, true);
+                FocusManager.Instance.Focus(descendent, true);
+                return true;
             }
+            else if (parent != null)
+            {
+                var previous = parent.GetVisualChildren()
+                    .OfType<IInputElement>()
+                    .Where(x => x.Focusable)
+                    .Reverse()
+                    .SkipWhile(x => x != element)
+                    .Skip(1)
+                    .FirstOrDefault();
+
+                if (previous != null)
+                {
+                    FocusManager.Instance.Focus(previous, true);
+                    return true;
+                }
+            }
+
+            return false;
         }
     }
 }

Perspex.Input/Perspex.Input.csproj

@@ -66,6 +66,7 @@
     <Compile Include="IInputElement.cs" />
     <Compile Include="IInputManager.cs" />
     <Compile Include="IKeyboardDevice.cs" />
+    <Compile Include="IKeyboardNavigation.cs" />
     <Compile Include="IMouseDevice.cs" />
     <Compile Include="InputElement.cs" />
     <Compile Include="InputExtensions.cs" />

Perspex.SceneGraph/VisualTree/VisualExtensions.cs

@@ -102,18 +102,5 @@ namespace Perspex.VisualTree
         {
             return visual.VisualParent as T;
         }
-
-        public static IEnumerable<IVisual> GetVisualSiblings(this IVisual visual)
-        {
-            IVisual parent = visual.VisualParent;
-
-            if (parent != null)
-            {
-                foreach (IVisual sibling in parent.VisualChildren)
-                {
-                    yield return sibling;
-                }
-            }
-        }
     }
 }