Fixing issue with announcing of PropertyGrid expanded state

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.