Panel Background image moving

using System;
using System.Windows.Forms;
using System.Drawing;
using System.Runtime.InteropServices;
public class MyPanel : Panel 
{ 
	public MyPanel() 
	{ 
		this.AutoScroll = true; 
		this.SetStyle(ControlStyles.SupportsTransparentBackColor, true); 
		this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true); 
	} 
	
	private Image mImage; 
	public Image Image 
	{ 
		get { return mImage; } 
		set 
		{ 
			mImage = value; 
			Invalidate(); 
		} 
	} 
	protected override void OnScroll(ScrollEventArgs se) 
	{ 
		if (se.Type == ScrollEventType.First) 
		{ 
			LockWindowUpdate(this.Handle); 
		} 
		else if (
				se.Type == ScrollEventType.ThumbTrack || 
				se.Type == ScrollEventType.ThumbPosition) 
		{ 
			LockWindowUpdate(IntPtr.Zero); 
			this.Refresh(); 
			LockWindowUpdate(this.Handle); 
		} 
		else 
		{ 
			LockWindowUpdate(IntPtr.Zero); 
			this.Invalidate(); 
		} 
		base.OnScroll(se); 
	} 
	
	protected override void OnPaint(PaintEventArgs e) 
	{ 
		using (SolidBrush br = new SolidBrush(this.BackColor)) 
		{ 
			e.Graphics.FillRectangle(br, this.ClientRectangle); 
		} 
		if (mImage != null) 
		{ 
			e.Graphics.DrawImage(mImage, 0, 0); 
		} 
		base.OnPaint(e); 
	} 
	[DllImport("user32.dll")] 
	private static extern bool LockWindowUpdate(IntPtr hWnd);
}