Add MSAA focus event on ComboBox dropdown close (#8220)

* Add MSAA focus event on ComboBox dropdown close Fixes #8218 This event lets NVDA correctly switch focus from dropdown to ComboBox edit field when dropdown is closed. NVDA recognizes ComboBox as IAccessible object, therefore it ignores existing UIA focus events. * Improve comment with explanation of childID value Co-authored-by: Tanya Solyanik <[email protected]> Co-authored-by: Tanya Solyanik <[email protected]>
dotnet · Nov 17, 2022 · 572929b · 572929b
1 parent 2a92763
commit 572929b
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/src/System.Windows.Forms/src/System/Windows/Forms/ComboBox.cs b/src/System.Windows.Forms/src/System/Windows/Forms/ComboBox.cs
@@ -3058,6 +3058,11 @@ protected virtual void OnDropDownClosed(EventArgs e)
                     AccessibilityObject.RaiseAutomationEvent(UiaCore.UIA.AutomationFocusChangedEventId);
                 }
 
+                // Some accessibility tools (e.g., NVDA) could recognize ComboBox as IAccessible object
+                // and ignore UIA focus change event. For such cases we need to additionaly raise MSAA focus event.
+                // childID = CHILDID_SELF - 1 (the -1 will resolve to CHILDID_SELF when we call NotifyWinEvent)
+                AccessibilityNotifyClients(AccessibleEvents.Focus, childID: -1);
+
                 // Notify Collapsed/expanded property change.
                 AccessibilityObject.RaiseAutomationPropertyChangedEvent(
                     UiaCore.UIA.ExpandCollapseExpandCollapseStatePropertyId,