编写资源管理器求助！

我这里有个例子，获取任意文件的图标：using System;
using System.Windows.Forms;
using System.Drawing;namespace MyForm {
public class CreatedForm : System.Windows.Forms.Form
{
private System.Windows.Forms.Button button;
private Label label;
        public static void Main( )
                {
                        Application.Run( new  CreatedForm( ) );
                }
public CreatedForm()
{
InitializeComponents();
}

void InitializeComponents() {
// 
//  Set up generated class form
// 
this.SuspendLayout();
this.Name = "form";
this.Size = new System.Drawing.Size(200, 96);
this.Text = "Test";

// 
//  Set up member button
// 
button = new System.Windows.Forms.Button();
button.Name = "button";
button.Location = new System.Drawing.Point(56, 24);
button.Size = new Size(100,22);
button.Text = "按钮";
button.Anchor = (System.Windows.Forms.AnchorStyles.Top|System.Windows.Forms.AnchorStyles.Left);
button.TabIndex = 0;
this.Controls.Add(button);
button.Click+=new EventHandler(this.button_Click);
this.ResumeLayout(false);
//
label = new Label();
//label.Text = "文件图标";
label.Location=new Point(5,5);
label.Size = new Size(40,40);
this.Controls.Add(label);
}
      protected void button_Click(object sender, System.EventArgs e)
              {
                        //Stream myStream;
                        OpenFileDialog openFileDialog1 = new OpenFileDialog();
openFileDialog1.InitialDirectory = "c:\\" ;
openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*" ;
openFileDialog1.FilterIndex = 2 ;
openFileDialog1.RestoreDirectory = true ;
if(openFileDialog1.ShowDialog() == DialogResult.OK)
                        {
                          if((openFileDialog1.OpenFile())!= null)
                          {
   //label.Text=openFileDialog1.FileName;
   label.Image=WindowsAppTmp.ExtractIcon.GetIcon(openFileDialog1.FileName, false).ToBitmap();
   //Console.WriteLine(openFileDialog1.FileName);
                          }
                        }
             }
}
}using System;
using System.Runtime.InteropServices;
using System.Drawing;
namespace WindowsAppTmp
{
public class ExtractIcon
{
[DllImport("Shell32.dll")]
private static extern int  SHGetFileInfo
(
string pszPath,
uint dwFileAttributes,
out SHFILEINFO psfi,
uint cbfileInfo,
SHGFI uFlags
); [StructLayout(LayoutKind.Sequential)]
private struct SHFILEINFO
{
public SHFILEINFO(bool b)
{
hIcon=IntPtr.Zero;iIcon=0;dwAttributes=0;szDisplayName="";szTypeName="";
}
public IntPtr hIcon;
public int iIcon;
public uint dwAttributes;
[MarshalAs(UnmanagedType.LPStr, SizeConst=260)]
public string szDisplayName;
[MarshalAs(UnmanagedType.LPStr, SizeConst=80)]
public string szTypeName;
}; private ExtractIcon()
{
} private enum SHGFI
{
SmallIcon   = 0x00000001,
LargeIcon   = 0x00000000,
Icon    = 0x00000100,
DisplayName   = 0x00000200,
Typename   = 0x00000400,
SysIconIndex  = 0x00004000,
UseFileAttributes = 0x00000010
}
public static Icon GetIcon(string strPath, bool bSmall)
{
SHFILEINFO info = new SHFILEINFO(true);
int cbFileInfo = Marshal.SizeOf(info);
SHGFI flags;
if (bSmall)
flags = SHGFI.Icon|SHGFI.SmallIcon|SHGFI.UseFileAttributes;
else
flags = SHGFI.Icon|SHGFI.LargeIcon|SHGFI.UseFileAttributes; SHGetFileInfo(strPath, 256, out info,(uint)cbFileInfo, flags);
return Icon.FromHandle(info.hIcon);
}
}
}