C#

public interface IWidgetA
{
    object wa
    {
        get;
        set;
    }
}
public interface IWidgetB
{
    object wb
    {
        get;
        set;
    }
}
public interface IWidgetC
{
    object wc
    {
        get;
        set;
    }
}

public class AllWidgets : IWidgetA, IWidgetB, IWidgetC
{
    protected object _wa;
    public object wa
    {
        get { return _wa; }
        set { _wa = value; }
    }

    protected object _wb;
    public object wb
    {
        get { return _wb; }
        set { _wb = value; }
    }

    protected object _wc;
    public object wc
    {
        get { return _wc; }
        set { _wc = value; }
    }
}

// Using the interface definitions from the previous section...
public class WidgetAImpl : IWidgetA
{
    protected object _wa;
    public object wa
    {
        get { return _wa; }
        set { _wa = value; }
    }
}
public class WidgetBImpl : IWidgetB
{
    protected object _wb;
    public object wb
    {
        get { return _wb; }
        set { _wb = value; }
    }
}
public class WidgetCImpl : IWidgetC
{
    protected object _wc;
    public object wc
    {
        get { return _wc; }
        set { _wc = value; }
    }
}

public class AllWidgets : IWidgetA, IWidgetB, IWidgetC
{
    protected WidgetAImpl;
    protected WidgetBImpl;
    protected WidgetCImpl;

    public object wa
    {
        get { return this.WidgetAImpl.wa; }
        set { this.WidgetAImpl.wa = value; }
    }

    public object wb
    {
        get { return this.WidgetBImpl.wb; }
        set { this.WidgetBImpl.wb = value; }
    }

    public object wc
    {
        get { return this.WidgetCImpl.wc; }
        set { this.WidgetCImpl.wc = value; }
    }

}

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
public struct FileInfo
{
	[MarshalAs(UnmanagedType.U4)]public int ID;
	[MarshalAs(UnmanagedType.U4)]public FilePermissions Permissions;
	[MarshalAs(UnmanagedType.U4)]public int Locks;
	[MarshalAs(UnmanagedType.LPWStr)]public string Path;
	[MarshalAs(UnmanagedType.LPWStr)]public string Username;
}
[Flags]
public enum FilePermissions
{
	Read = 1,
	Write = 2,
	Create = 4
}
public class NetFiles
{
  private const int ErrorFileNotFound = 2;
  private const int ErrorAccessDenied = 5;
  private const int ErrorMoreData = 234;
  private const int MaxPreferredLength = -1;
  private const int BufferSize = 4000;

  [DllImport("netapi32.dll", CharSet=CharSet.Unicode)]
  private static extern int NetFileEnum
  (
    [MarshalAs(UnmanagedType.LPWStr)]string serverName,
    [MarshalAs(UnmanagedType.LPWStr)]string basePath,
    [MarshalAs(UnmanagedType.LPWStr)]string userName,
    [MarshalAs(UnmanagedType.U4)]int level,
    [MarshalAs(UnmanagedType.SysUInt), Out]out IntPtr buffer,
    [MarshalAs(UnmanagedType.U4)]int preferredMaxLength,
    [MarshalAs(UnmanagedType.U4), Out]out int entriesRead,
    [MarshalAs(UnmanagedType.U4), Out]out int totalEntries,
    [MarshalAs(UnmanagedType.U4), In, Out]ref int resumeHandle
  );

  [DllImport("netapi32.dll", CharSet=CharSet.Unicode)]
  private static extern int NetFileClose
  (
    [MarshalAs(UnmanagedType.LPWStr)]string serverName,
    [MarshalAs(UnmanagedType.U4)]int fileID
  );

  [DllImport("netapi32.dll")]
  private static extern int NetApiBufferFree
  (
    IntPtr buffer
  );
  private NetFiles()
  {
  }
  public static IList GetOpenFiles()
  {
    return GetOpenFiles(null, null, null);
  }
  public static IList GetOpenFilesOnServer(string server)
  {
    return GetOpenFiles(server, null, null);
  }
  public static IList GetOpenFilesWithPath(string basePath)
  {
    return GetOpenFiles(null, basePath, null);
  }
  public static IList GetOpenFilesForUsername(string username)
  {
    return GetOpenFiles(null, null, username);
  }
  public static IList GetOpenFiles(string server, string basePath,
  	string username)
  {
    IntPtr buffer;
    int entriesRead;
    int totalEntries;
    int resumeHandle = 0;
    ArrayList list = new ArrayList();

    int retVal = NetFileEnum(server, basePath, username, 3, out buffer,
      BufferSize, out entriesRead, out totalEntries, ref resumeHandle);
    while ((retVal == 0 || retVal == ErrorMoreData) && buffer != IntPtr.Zero)
    {
      for (int i=0; i<entriesRead; i++)
      {
        IntPtr address = new IntPtr(buffer.ToInt32() + i *
			Marshal.SizeOf(typeof(FileInfo)));
        if (address != IntPtr.Zero)
        {
          FileInfo info = (FileInfo)Marshal.PtrToStructure(address,
		  	typeof(FileInfo));
          list.Add(info);
        }
      }

      NetApiBufferFree(buffer);

      if (retVal == ErrorMoreData)
        retVal = NetFileEnum(server, basePath, username, 3, out buffer,
          MaxPreferredLength, out entriesRead, out totalEntries, ref resumeHandle);
      else break;
    }

    if (retVal == 0) return list;
    else if (retVal == 5) throw new SecurityException("Access denied");
    else throw new System.ComponentModel.Win32Exception(retVal);
  }
  public static void CloseFile(int handle)
  {
    CloseFile(handle, null);
  }
  public static void CloseFile(int handle, string server)
  {
    int retVal = NetFileClose(server, handle);
    if (retVal == 0) return;
    else if (retVal == ErrorAccessDenied)
      throw new SecurityException("Access denied");
    else if (retVal == ErrorFileNotFound)
      throw new System.IO.FileNotFoundException("The file was not found.");
    else throw new System.ComponentModel.Win32Exception(retVal);
  }
}

Heath Stewart wrote:

To get open file handles on the local machine

Heath Stewart wrote:

uses a bunch of undocumented APIs

Heath Stewart wrote:

You can, however, find an application that does this called "Handle" on http://www.sysinternals.com[^].

cbApplication.DataSource = dsApplication.Tables(0)
cbApplication.DataTextField = "DirectoryName"
cbApplication.DataValueField = "IDDirectory"
cbApplication.DataBind()