//        static RenderElement HitTestOnPreviousChain(HitChain hitPointChain, HitChain previousChain, int x, int y)
        //        {
        //#if DEBUG
        //            if (hitPointChain == previousChain)
        //            {
        //                throw new NotSupportedException();
        //            }
        //#endif

        //            if (previousChain.Count > 0)
        //            {
        //                previousChain.SetStartTestPoint(x, y);
        //                //test on prev chain top to bottom
        //                int j = previousChain.Count;
        //                for (int i = 0; i < j; ++i)
        //                {
        //                    HitInfo hitInfo = previousChain.GetHitInfo(i);
        //                    RenderElement elem = hitInfo.HitElemAsRenderElement;
        //                    if (elem != null && elem.VisibleAndHasParent)
        //                    {
        //                        if (elem.Contains(hitInfo.point))
        //                        {
        //                            RenderElement found = elem.FindUnderlyingSiblingAtPoint(hitInfo.point);
        //                            if (found == null)
        //                            {
        //                                Point leftTop = elem.Location;
        //                                hitPointChain.OffsetTestPoint(leftTop.X, leftTop.Y);
        //                                hitPointChain.AddHitObject(elem);
        //                                //add to chain
        //                            }
        //                            else
        //                            {
        //                                break;
        //                            }
        //                        }
        //                    }
        //                    else
        //                    {
        //                        break;
        //                    }
        //                }
        //            }
        //            //---------------------------------
        //            if (hitPointChain.Count > 0)
        //            {
        //                var commonElement = hitPointChain.GetHitInfo(hitPointChain.Count - 1).HitElemAsRenderElement;
        //                hitPointChain.RemoveCurrentHit();
        //                return commonElement;
        //            }
        //            else
        //            {
        //                return null;
        //            }
        //        }


        void HitTestCoreWithPrevChainHint(HitChain hitChain, HitChain previousChain, int x, int y)
        {
            //---------------------------------
            //test on previous chain first , find common element
            hitChain.Reset();
            hitChain.SetStartTestPoint(x, y);
#if DEBUG
            hitChain.dbugHitPhase = _dbugHitChainPhase;
#endif
            //if (this.dbugId > 0 && isDragging && previousChain.Count > 1)
            //{

            //}

            //RenderElement commonElement = HitTestOnPreviousChain(hitPointChain, previousChain, x, y);

            //temp fix
            //TODO: fix bug on HitTestOnPreviousChain()
            RenderElement commonElement = _topRenderElement;
            commonElement.HitTestCore(hitChain);

            //remove disable elements
            //if (hitPointChain.dbugHitPhase == dbugHitChainPhase.MouseDown)
            //{
            int j = hitChain.Count;
            for (int i = 0; i < j; ++i)
            {
                HitInfo       info    = hitChain.GetHitInfo(i);
                RenderElement renderE = info.HitElemAsRenderElement;
                if (renderE != null && renderE.GetController() is IUIEventListener ui && !ui.Enabled)
                {
                    HitChain.UnsafeClear(hitChain);
                    break;//stop loop and exit
                }
            }
            //}
        }