C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Drawing.Imaging;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        private const int WM_SCROLL = 276; // Horizontal scroll
        private const int WM_VSCROLL = 277; // Vertical scroll
        private const int SB_LINEUP = 0; // Scrolls one line up
        private const int SB_LINELEFT = 0;// Scrolls one cell left
        private const int SB_LINEDOWN = 1; // Scrolls one line down
        private const int SB_LINERIGHT = 1;// Scrolls one cell right
        private const int SB_PAGEUP = 2; // Scrolls one page up
        private const int SB_PAGELEFT = 2;// Scrolls one page left
        private const int SB_PAGEDOWN = 3; // Scrolls one page down
        private const int SB_PAGERIGTH = 3; // Scrolls one page right
        private const int SB_PAGETOP = 6; // Scrolls to the upper left
        private const int SB_LEFT = 6; // Scrolls to the left
        private const int SB_PAGEBOTTOM = 7; // Scrolls to the upper right
        private const int SB_RIGHT = 7; // Scrolls to the right
        private const int SB_ENDSCROLL = 8; // Ends scroll

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        private static extern int SendMessage(IntPtr hWnd, int wMsg, IntPtr wParam, IntPtr lParam);
   
        List<point> pointList = new List<point>();

        Graphics graphics;
        Pen pen;
        Random random = new Random();
        int current = 0;
        Point oldPoint = new Point();
        Point newPoint = new Point();
        Color bgColor;
        Bitmap newBitmap;

        public Form1()
        {
            InitializeComponent();

            bgColor = Color.White;
            pen = new Pen(Color.Black);
            newBitmap = new Bitmap(pbChart.Width, pbChart.Height, PixelFormat.Format24bppRgb);
            graphics = Graphics.FromImage(newBitmap);
            graphics.Clear(bgColor);

            graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
        }

        void drawPoint(int px, int py)
        {
            newPoint.X = px;
            newPoint.Y = py;

            if (pointList.Count != 0)
            {
                oldPoint = pointList.Last();
            }
            else
            {
                oldPoint = newPoint;
            }

            pointList.Clear();

            pointList.Add(oldPoint);
            pointList.Add(newPoint);

            if (px > pbChart.Width)
            {
                pbChart.Width += (px - pbChart.Width);
                SendMessage(panel1.Handle, WM_SCROLL, (IntPtr)SB_RIGHT, IntPtr.Zero);
            }

            graphics.DrawCurve(pen, pointList.ToArray());

            pbChart.BackgroundImage = newBitmap;

            pbChart.Refresh();
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            drawPoint(current, random.Next(0, pbChart.Height));
            current += 5;
        }

        private void btnPlayPause_Click(object sender, EventArgs e)
        {
            if (timer1.Enabled)
                timer1.Stop();
            else
                timer1.Start();
        }
    }
}</point></point>

public sealed class MyPagerSettings : IStateManager {

...
	[Category("Appearance")]
	[DefaultValue(true)]
	[NotifyParentProperty(true)]
	public bool Visible {
		get { return (bool?)mViewState["Visible"] ?? true; }
		set { mViewState["Visible"] = value; }
	}

...
}

public class MyGridView : GridView {

...

	MyPagerSettings mPagerSettings;


	[Category("Paging")]
	[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
	[NotifyParentProperty(true)]
	[PersistenceMode(PersistenceMode.InnerProperty)]
	<code>new</code> public virtual MyPagerSettings PagerSettings {
		get {
			if (mPagerSettings == null) {
				mPagerSettings = new MyPagerSettings(this);
				if (IsTrackingViewState)
					((IStateManager)mPagerSettings).TrackViewState();
			}
			return mPagerSettings;
		}
	}

...

}

			<awc:MyGridView ID="MyGridView1" runat="server" AllowPaging="True" PageSize="10">
				<code><PagerSettings Visible=false />   <-- The error happens here!</code>
				<Columns>
...
				</Columns>
			</awc:MyGridView>