I think the problem is being reproduced due to competitive requests t…

…o Narrator. Periodically it announces expanded state information and periodically skips.

A possible fix is to replace the standard method "RaiseAutomationPropertyChangedEvent" with the "RaiseAutomationNotification" method. In this case, we force the expanded state information to be announced, which helps avoid a possible contention problem.

src/System.Windows.Forms/src/Resources/SR.resx

@@ -6907,6 +6907,9 @@ Stack trace where the illegal operation occurred was:
  <data name="EditDefaultAccessibleName" xml:space="preserve">
  <value>Spinner</value>
  </data>
+ <data name="ExpandedStateName" xml:space="preserve">
+ <value>Expanded</value>
+ </data>
  <data name="ListViewItemAccessibilityObjectRequiresListView" xml:space="preserve">
  <value>Cannot get accessiblity object when ListViewItem is not attached to a ListView.</value>
  </data>

src/System.Windows.Forms/src/System/Windows/Forms/PropertyGridInternal/PropertyGridView.cs

@@ -1494,10 +1494,10 @@ public void DropDownControl(Control control)
  if (gridEntry is not null && IsAccessibilityObjectCreated)
  {
  gridEntry.AccessibilityObject.RaiseAutomationEvent(UiaCore.UIA.AutomationFocusChangedEventId);
- gridEntry.AccessibilityObject.RaiseAutomationPropertyChangedEvent(
- UiaCore.UIA.ExpandCollapseExpandCollapseStatePropertyId,
- UiaCore.ExpandCollapseState.Collapsed,
- UiaCore.ExpandCollapseState.Expanded);
+ gridEntry.AccessibilityObject.InternalRaiseAutomationNotification(
+ Automation.AutomationNotificationKind.Other,
+ Automation.AutomationNotificationProcessing.ImportantMostRecent,
+ SR.ExpandedStateName);
  }
 
  // Control is a top level window. Standard way of setting parent on the control is prohibited for top-level controls.

src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/PropertyGridInternal/PropertyGridViewTests.cs

@@ -3,6 +3,8 @@
 // See the LICENSE file in the project root for more information.
 
 using Xunit;
+using System.ComponentModel;
+using System.Windows.Forms.Automation;
 
 namespace System.Windows.Forms.PropertyGridInternal.Tests
 {
@@ -18,5 +20,83 @@ public void PropertyGridView_Ctor_Default()
 
  Assert.NotNull(propertyGridView);
  }
+
+ [WinFormsFact]
+ public void PropertyGridView_GridEntry_AccessibleObject_GetsNotification()
+ {
+ using PropertyGrid propertyGrid = new();
+ propertyGrid.CreateControl();
+ PropertyGridView propertyGridView = propertyGrid.TestAccessor().Dynamic._gridView;
+ AccessibleObject propertyGridViewAccessibilityObject = propertyGridView.AccessibilityObject;
+ TestGridEntry parent = new(propertyGrid, parent: null, propertyGridView);
+ PropertyDescriptor propertyDescriptor = TypeDescriptor.GetProperties(typeof(TestEntity)).
+ Find(nameof(TestEntity.SizeProperty), ignoreCase: false);
+
+ GridEntryWithCustomAccessibleObject testGridEntry = new(propertyGrid, parent, propertyDescriptor, hide: false);
+ GridEntryAccessibleObjectWithNotificationCounter accessibleObject = (GridEntryAccessibleObjectWithNotificationCounter)testGridEntry.AccessibilityObject;
+ Assert.Equal(0, accessibleObject.RaiseAutomationNotificationCallCount);
+
+ using Button button = new();
+ propertyGrid.SelectedObject = button;
+ GridEntryCollection gridEntries = propertyGridView.TestAccessor().Dynamic._allGridEntries;
+ gridEntries.Insert(0, testGridEntry);
+
+ propertyGridView.SelectedGridEntry = testGridEntry;
+ GridEntry selectedGridEntry = propertyGridView.TestAccessor().Dynamic._selectedGridEntry;
+ int selectedRow = propertyGridView.TestAccessor().Dynamic._selectedRow;
+
+ Assert.True(propertyGridView.IsAccessibilityObjectCreated);
+ Assert.Equal(testGridEntry, selectedGridEntry);
+ Assert.Equal(testGridEntry, gridEntries[selectedRow]);
+ propertyGridView.DropDownControl(new Control());
+
+ Assert.Equal(1, accessibleObject.RaiseAutomationNotificationCallCount);
+ Assert.True(propertyGrid.IsHandleCreated);
+ Assert.True(propertyGridView.IsHandleCreated);
+ }
+
+ private class TestGridEntry : GridEntry
+ {
+ private readonly PropertyGridView _propertyGridView;
+
+ public TestGridEntry(PropertyGrid ownerGrid, GridEntry parent, PropertyGridView propertyGridView)
+ : base(ownerGrid, parent)
+ {
+ _propertyGridView = propertyGridView;
+ }
+
+ internal override PropertyGridView OwnerGridView => _propertyGridView;
+ }
+
+ private class GridEntryWithCustomAccessibleObject : PropertyDescriptorGridEntry
+ {
+ public GridEntryWithCustomAccessibleObject(PropertyGrid ownerGrid, GridEntry parent, PropertyDescriptor propertyDescriptor, bool hide)
+ : base(ownerGrid, parent, propertyDescriptor, hide)
+ {
+ }
+
+ protected override GridEntryAccessibleObjectWithNotificationCounter GetAccessibilityObject() => new(this);
+ }
+
+ private class GridEntryAccessibleObjectWithNotificationCounter : GridEntry.GridEntryAccessibleObject
+ {
+ public GridEntryAccessibleObjectWithNotificationCounter(GridEntry owner) : base(owner)
+ {
+ }
+
+ public int RaiseAutomationNotificationCallCount { get; private set; }
+
+ internal override bool InternalRaiseAutomationNotification(AutomationNotificationKind notificationKind,
+ AutomationNotificationProcessing notificationProcessing, string notificationText)
+ {
+ RaiseAutomationNotificationCallCount++;
+ return base.InternalRaiseAutomationNotification(notificationKind, notificationProcessing, notificationText);
+ }
+ }
+
+ internal class TestEntity
+ {
+ public System.Drawing.Size SizeProperty { get; set; }
+ }
  }
 }