WPF implement VirtualizingPanel IScrollInfo, not trigger MeasureOverride/ArrangeOverride/SetVerticalOffset/SetHorizontalOffset when scrolling

Question

I am implementing my own VirtualizingPanel with IScrollInfo interface, and scroll behavior is weird normal behavior I want to like StackPanel, panel move with dragging the scroll bar

my implement, pannel does not move when dragging, SetHorizontalOffset/MeasureOverride also not trigger. And pannel only move after mouse release.

I realize MeasureOverride/ArrangeOverride will be triggered all the time when dragging scroll bar, but my pannel only triggers once after mouse release.

My code file is long, and I paste a part of the code that I think is important.

public class MyVirtualizingPanel : VirtualizingPanel, IScrollInfo
{

        public void LineLeft()
        {
            SetHorizontalOffset(HorizontalOffset - ScrollHorizonLineSize);
        }

        public void LineRight()
        {
            SetHorizontalOffset(HorizontalOffset + ScrollHorizonLineSize);
        }


        public void SetHorizontalOffset(double offset)
        {
            if (offset < 0 || ViewportWidth >= ExtentWidth)
            {
                offset = 0;
            }
            else if (offset + ViewportWidth >= ExtentWidth)
            {
                offset = ExtentWidth - ViewportWidth;
            }
            Offset = new Point(offset, Offset.Y);
            ScrollOwner?.InvalidateScrollInfo();
            InvalidateMeasure();
        }

        protected override Size MeasureOverride(Size availableSize)
        {
            // update scoll size

            if (ViewPort != availableSize)
            {
                ViewPort = availableSize;
                this.ScrollOwner.InvalidateScrollInfo();
            }

            var extent = CalcExtent(availableSize);
            if (extent != Extent)
            {
                Extent = extent;
                this.ScrollOwner.InvalidateScrollInfo();
            }

            // virtualizing 
            // ...

            return Extent;
        }

        protected override Size ArrangeOverride(Size finalSize)
        {
            for (int index = 0; index < InternalChildren.Count; index++)
            {
                child.Arrange(CalcChildRect(index));
            }
            return finalSize;
        }
}

What should I do?