[a11y][WPF] Fix accessibility focus handling for spin buttons

Previously, if a spin button had the focus, the narrator wouldn't see
it. We also reported to automation clients that spin buttons weren't
focusable. This fixes both of those issues. Now the spin button
having the focus is treated basically the same as the text box
inside the spinner control having the focus, as it's the text box
that gets focus when the user tabs to it.

1 files changed, 34 insertions, 8 deletions

diff --git a/Xwt.WPF/Xwt.WPFBackend/WindowsSpinButton.xaml.cs b/Xwt.WPF/Xwt.WPFBackend/WindowsSpinButton.xaml.cs
index 9c6d41fe..361b91b4 100644
--- a/Xwt.WPF/Xwt.WPFBackend/WindowsSpinButton.xaml.cs
+++ b/Xwt.WPF/Xwt.WPFBackend/WindowsSpinButton.xaml.cs
@@ -1,4 +1,4 @@
-//
+//
 // WindowsSpinButton.cs
 //
 // Author:
@@ -157,7 +157,7 @@ namespace Xwt.WPFBackend
 
         #region General
         Grid mainGrid;
-        TextBox textBox;
+        SpinButtonTextBox textBox;
         RepeatButton buttonUp;
         RepeatButton buttonDown;
         public WindowsSpinButton()
@@ -168,8 +168,8 @@ namespace Xwt.WPFBackend
             mainGrid.ColumnDefinitions.Add(new ColumnDefinition() { Width = new GridLength(1, GridUnitType.Star) });
             mainGrid.ColumnDefinitions.Add(new ColumnDefinition() { Width = new GridLength(16) });
 
-            //Textbox
-            textBox = new TextBox();
+			//Textbox
+			textBox = new SpinButtonTextBox (this);
             textBox.Text = "0";
             textBox.HorizontalAlignment = HorizontalAlignment.Stretch;
             textBox.MinWidth = 25;
@@ -247,8 +247,9 @@ namespace Xwt.WPFBackend
             }
         }
 
+	    public TextBox TextBox => textBox;
 
-        private void UserControl_Loaded(object sender, RoutedEventArgs e)
+	    private void UserControl_Loaded(object sender, RoutedEventArgs e)
         {
             UpdateTextbox();
         }
@@ -458,9 +459,19 @@ namespace Xwt.WPFBackend
 		#endregion
 
 		#region Accessibility
-		protected override AutomationPeer OnCreateAutomationPeer ()
-		{
-			return new WindowsSpinButtonAutomationPeer (this);
+	    class SpinButtonTextBox : TextBox
+	    {
+		    WindowsSpinButton spinButton;
+
+			public SpinButtonTextBox (WindowsSpinButton spinButton)
+			{
+				this.spinButton = spinButton;
+			}
+
+		    protected override AutomationPeer OnCreateAutomationPeer ()
+		    {
+			    return new WindowsSpinButtonAutomationPeer (spinButton);
+		    }
 		}
 
 		class WindowsSpinButtonAutomationPeer : UserControlAutomationPeer, IRangeValueProvider
@@ -486,6 +497,21 @@ namespace Xwt.WPFBackend
 				return AutomationControlType.Spinner;
 			}
 
+			protected override bool IsKeyboardFocusableCore ()
+			{
+				return true;
+			}
+
+			protected override bool HasKeyboardFocusCore ()
+			{
+				return Button.TextBox.IsFocused;
+			}
+
+			protected override void SetFocusCore ()
+			{
+				Button.TextBox.Focus ();
+			}
+
 			public override object GetPattern (PatternInterface patternInterface)
 			{
 				if (patternInterface == PatternInterface.RangeValue) {