System.Windows.Automation.Automation.RemoveStructureChangedEventHandler C# (CSharp) Method

        public static void RemoveStructureChangedEventHandler(AutomationElement element, StructureChangedEventHandler eventHandler)
        {
            Utility.ValidateArgumentNonNull(element, "element");
            Utility.ValidateArgumentNonNull(eventHandler, "eventHandler");

            try
            {
                StructureEventListener listener = (StructureEventListener)ClientEventList.Remove(AutomationElement.StructureChangedEvent, element, eventHandler);
                Factory.RemoveStructureChangedEventHandler(element.NativeElement, listener);
            }
            catch (System.Runtime.InteropServices.COMException e)
            {
                Exception newEx; if (Utility.ConvertException(e, out newEx)) { throw newEx; } else { throw; }
            }
        }

        public void StructureEventTest()
        {
            List <AutomationElement>     elementEventSenders      = new List <AutomationElement> ();
            List <StructureChangeType>   elementEventChangeTypes  = new List <StructureChangeType> ();
            List <AutomationElement>     childrenEventSenders     = new List <AutomationElement> ();
            List <StructureChangeType>   childrenEventChangeTypes = new List <StructureChangeType> ();
            StructureChangedEventHandler elementHandler           = delegate(object sender, StructureChangedEventArgs args) {
                elementEventSenders.Add(sender as AutomationElement);
                elementEventChangeTypes.Add(args.StructureChangeType);
            };

            At.AddStructureChangedEventHandler(panel1Element, TreeScope.Element, elementHandler);
            StructureChangedEventHandler childrenHandler = delegate(object sender, StructureChangedEventArgs args) {
                childrenEventSenders.Add(sender as AutomationElement);
                childrenEventChangeTypes.Add(args.StructureChangeType);
            };

            At.AddStructureChangedEventHandler(panel1Element, TreeScope.Children, childrenHandler);
            InvokePattern addAction    = (InvokePattern)btnAddTextboxElement.GetCurrentPattern(InvokePattern.Pattern);
            InvokePattern removeAction = (InvokePattern)btnRemoveTextboxElement.GetCurrentPattern(InvokePattern.Pattern);

            addAction.Invoke();
            Thread.Sleep(1000);
            Assert.AreEqual(1, elementEventSenders.Count, "Check event count");
            Assert.AreEqual(panel1Element, elementEventSenders [0], "Check ChildrenInvalidated event sender");
            Assert.AreEqual(StructureChangeType.ChildrenInvalidated,
                            elementEventChangeTypes [0], "Check ChildrenInvalidated event type");
            Assert.AreEqual(1, childrenEventSenders.Count, "Check event count");
            Assert.AreEqual(StructureChangeType.ChildAdded,
                            childrenEventChangeTypes [0], "Check ChildAdded event type");
            removeAction.Invoke();
            Thread.Sleep(1000);
            Assert.AreEqual(3, elementEventSenders.Count, "Check event count");
            Assert.AreEqual(panel1Element, elementEventSenders [1], "Check event sender");
            Assert.AreEqual(panel1Element, elementEventSenders [2], "Check event sender");
            Assert.IsTrue((elementEventChangeTypes [1] == StructureChangeType.ChildRemoved &&
                           elementEventChangeTypes [2] == StructureChangeType.ChildrenInvalidated) ||
                          (elementEventChangeTypes [1] == StructureChangeType.ChildrenInvalidated &&
                           elementEventChangeTypes [2] == StructureChangeType.ChildRemoved),
                          "Check event type");
            addAction.Invoke();
            Thread.Sleep(1000);
            Assert.AreEqual(4, elementEventSenders.Count, "Check event count");
            Assert.AreEqual(panel1Element, elementEventSenders [3], "Check ChildrenInvalidated event sender");
            Assert.AreEqual(StructureChangeType.ChildrenInvalidated,
                            elementEventChangeTypes [3], "Check ChildrenInvalidated event type");
            Assert.AreEqual(2, childrenEventSenders.Count, "Check event count");
            Assert.AreEqual(StructureChangeType.ChildAdded,
                            childrenEventChangeTypes [1], "Check ChildAdded event type");

            At.RemoveStructureChangedEventHandler(panel1Element, elementHandler);
            At.RemoveStructureChangedEventHandler(panel1Element, childrenHandler);
            addAction.Invoke();
            Thread.Sleep(1000);
            Assert.AreEqual(4, elementEventSenders.Count, "Element event count didn't change");
            Assert.AreEqual(2, childrenEventSenders.Count, "Children event count didn't change");
        }