Make narrator not announce menu item posistion

.NET Framework 4.8 added the PositionInSet automation property. It also changed the semantics so that if this
property is not set it's computed automatically. And it's read by the narrator. The net result is that when
proppy is run in a .NET Framework 4.8 app (like Visual Studio), the narrator reads off the position of menu items
(e.g. "blah blah menu item 4 of 11"). AND hidden menu items are counted here, which makes those positions wrong,
causing this bug: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1000455.
To work around all of that, we set the PositionInSet property explicitly, when running on .NET Framework 4.8,
to be 0. That causes the narrator not to read the position at all, which is how most VS menus behave.

1 files changed, 23 insertions, 0 deletions

diff --git a/Xamarin.PropertyEditing.Windows/PropertyButton.cs b/Xamarin.PropertyEditing.Windows/PropertyButton.cs
index b5c210a..ee78b1b 100644
--- a/Xamarin.PropertyEditing.Windows/PropertyButton.cs
+++ b/Xamarin.PropertyEditing.Windows/PropertyButton.cs
@@ -11,6 +11,8 @@ using System.Windows.Input;
 using System.Windows.Media;
 using System.Windows.Shapes;
 using Xamarin.PropertyEditing.ViewModels;
+using System.Windows.Automation;
+using System.Reflection;
 
 namespace Xamarin.PropertyEditing.Windows
 {
@@ -87,6 +89,25 @@ namespace Xamarin.PropertyEditing.Windows
 				MenuItem customExpression = this.menu.Items.OfType<MenuItem>().FirstOrDefault (mi => mi.Name == "CustomExpressionItem");
 				if (customExpression != null)
 					customExpression.Click += OnCustomExpression;
+
+				if (!initializedSetPositionInSetMethod) {
+					setPositionInSetMethod = typeof (AutomationProperties).GetMethod ("SetPositionInSet");
+					initializedSetPositionInSetMethod = true;
+				}
+
+				// .NET Framework 4.8 added the PositionInSet automation property. It also changed the semantics so that if this
+				// property is not set it's computed automatically. And it's read by the narrator. The net result is that when
+				// proppy is run in a .NET Framework 4.8 app (like Visual Studio), the narrator reads off the position of menu items
+				// (e.g. "blah blah menu item 4 of 11"). AND hidden menu items are counted here, which makes those positions wrong,
+				// causing this bug: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1000455.
+				// To work around all of that, we set the PositionInSet property explicitly, when running on .NET Framework 4.8,
+				// to be 0. That causes the narrator not to read the position at all, which is how most VS menus behave.
+				if (setPositionInSetMethod != null) {
+					foreach (object item in this.menu.Items) {
+						if (item is MenuItem menuItem)
+							setPositionInSetMethod.Invoke (null, new object[] { menuItem, 0 });
+					}
+				}
 			}
 
 			this.menu.IsOpen = true;
@@ -100,6 +121,8 @@ namespace Xamarin.PropertyEditing.Windows
 		private Rectangle indicator;
 		private ContextMenu menu;
 		private PropertyViewModel vm;
+		private static bool initializedSetPositionInSetMethod;
+		private static MethodInfo setPositionInSetMethod;
 
 		private void OnBorderMouseDown (object sender, MouseButtonEventArgs e)
 		{