[Win] Ensure ChoiceControl deselects

In theory just checking one radio in the group should be enough, but in
some circumstances when VMs change it doesn't appear to be enough, so
we'll enforce it.

1 files changed, 19 insertions, 6 deletions

diff --git a/Xamarin.PropertyEditing.Windows/ChoiceControl.cs b/Xamarin.PropertyEditing.Windows/ChoiceControl.cs
index f80ad63..efba8c1 100644
--- a/Xamarin.PropertyEditing.Windows/ChoiceControl.cs
+++ b/Xamarin.PropertyEditing.Windows/ChoiceControl.cs
@@ -66,13 +66,17 @@ namespace Xamarin.PropertyEditing.Windows
 
 		protected override void OnSelectionChanged (SelectionChangedEventArgs e)
 		{
-			if (e.AddedItems.Count == 0) return;
-			var presenter = (ContentPresenter) ItemContainerGenerator.ContainerFromItem (e.AddedItems[0]);
-			if (presenter == null)
-				return;
+			if (e.RemovedItems.Count > 0) {
+				var removedToggle = GetToggle (e.RemovedItems[0]);
+				if (removedToggle != null)
+					removedToggle.IsChecked = false;
+			}
 
-			var toggle = (ToggleButton) VisualTreeHelper.GetChild (presenter, 0);
-			toggle.IsChecked = true;
+			if (e.AddedItems.Count > 0) {
+				var addedToggle = GetToggle (e.AddedItems[0]);
+				if (addedToggle != null)
+					addedToggle.IsChecked = true;
+			}
 		}
 
 		internal void FocusSelectedItem ()
@@ -87,6 +91,15 @@ namespace Xamarin.PropertyEditing.Windows
 			toggle.Focus ();
 		}
 
+		private ToggleButton GetToggle (object item)
+		{
+			var presenter = (ContentPresenter) ItemContainerGenerator.ContainerFromItem (item);
+			if (presenter == null)
+				return null;
+
+			return VisualTreeHelper.GetChild (presenter, 0) as ToggleButton;
+		}
+
 		private void OnItemContainerGeneratorOnStatusChanged (object sender, EventArgs args)
 		{
 			if (ItemContainerGenerator.Status != GeneratorStatus.ContainersGenerated)