#region License
// Desktop 1.1
//																																						*
// Copyright (C) 2004  http://www.onyeyiri.co.uk
// Coded by: Nnamdi Onyeyiri
//
// This code may be used in any way you desire except for commercial use.
// The code can be freely redistributed unmodified as long as all of the authors 
// copyright notices remain intact, as long as it is not being sold for profit.
// Although I have tried to ensure the stability of the code, I will not take 
// responsibility for any loss, damages, or death it may cause.
//
// This software is provided "as is" without any expressed or implied warranty.
//
// -------------------------
// Change Log
//
// Version 1.0:  -First Release
//
// Version 1.1:  -Added Window and WindowCollection classes
// 6/6/2004      -Added another GetWindows overload, that used WindowCollection
//               -Added GetInputProcesses method to retrieve processes on Input desktop
//               -Changed GetWindows and GetDesktops to return arrays, instead of them being passed by ref
//
// Version 1.2   -Implemented IDisposable
// 8/7/2004      -Implemented ICloneable
//               -Overrided ToString to return desktop name
//
// Version 2.0   -Switched to Generic Collections
// 7/19/2010     -Added enumeration of process from alternate desktops
// Joel Bennett  -Renamed a lot of methods to remove duplication
#endregion

using System;
using System.Threading;
using System.Text;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Collections.Generic;
using System.ComponentModel;

/// <summary>
/// Encapsulates the Desktop API.
/// </summary>
public class Desktop : IDisposable, ICloneable
{
   #region Imports
   [DllImport("kernel32.dll")]
   private static extern int GetThreadId(IntPtr thread);

   [DllImport("kernel32.dll")]
   private static extern int GetProcessId(IntPtr process);

   //
   // Imported winAPI functions.
   //
   [DllImport("user32.dll")]
   private static extern IntPtr CreateDesktop(string lpszDesktop, IntPtr lpszDevice, IntPtr pDevmode, int dwFlags, long dwDesiredAccess, IntPtr lpsa); 

   [DllImport("user32.dll")]
   private static extern bool CloseDesktop(IntPtr hDesktop);

   [DllImport("user32.dll")]
   private static extern IntPtr OpenDesktop(string lpszDesktop, int dwFlags, bool fInherit, long dwDesiredAccess);

   [DllImport("user32.dll")]
   private static extern IntPtr OpenInputDesktop(int dwFlags, bool fInherit, long dwDesiredAccess);

   [DllImport("user32.dll")]
   private static extern bool SwitchDesktop(IntPtr hDesktop);

   [DllImport("user32.dll")]
   private static extern bool EnumDesktops(IntPtr hwinsta, EnumDesktopProc lpEnumFunc, IntPtr lParam);

   [DllImport("user32.dll")]
   private static extern IntPtr GetProcessWindowStation();

   [DllImport("user32.dll")]
   private static extern bool EnumDesktopWindows(IntPtr hDesktop, EnumDesktopWindowsProc lpfn, IntPtr lParam);

   [DllImport("user32.dll")]
   private static extern bool SetThreadDesktop(IntPtr hDesktop);

   [DllImport("user32.dll")]
   public static extern IntPtr GetThreadDesktop(int dwThreadId);

   [DllImport("user32.dll")]
   [return: MarshalAs(UnmanagedType.Bool)]
   private static extern bool GetUserObjectInformation(IntPtr hObj, int nIndex, IntPtr pvInfo, int nLength, ref int lpnLengthNeeded);

   
   
   [DllImport("user32.dll")]
   private static extern int GetWindowText(IntPtr hWnd, IntPtr lpString, int nMaxCount);

   private delegate bool EnumDesktopProc(string lpszDesktop, IntPtr lParam);
   private delegate bool EnumDesktopWindowsProc(IntPtr desktopHandle, IntPtr lParam);

   
   // The Unicode version of this function, CreateProcessW, can modify the contents of the lpCommandLine string.
   // Therefore, you can't just pass a string (because it's a constant, so it becomes a pointer to read-only memory).
   [return: MarshalAs(UnmanagedType.Bool)][DllImport("kernel32.dll")]
   private static extern bool CreateProcess( string lpApplicationName, string lpCommandLine, IntPtr lpProcessAttributes, IntPtr lpThreadAttributes, bool bInheritHandles, int dwCreationFlags,  IntPtr lpEnvironment,  string lpCurrentDirectory,  [In] ref STARTUPINFO lpStartupInfo, [Out]out PROCESS_INFORMATION lpProcessInformation);

   [StructLayout(LayoutKind.Sequential)]
   private struct PROCESS_INFORMATION 
   {
      public IntPtr hProcess;
      public IntPtr hThread;
      public int dwProcessId;
      public int dwThreadId;
   }

   [StructLayout(LayoutKind.Sequential)]
   private struct STARTUPINFO 
   {
      public int cb;
      public string lpReserved;
      public string lpDesktop;
      public string lpTitle;
      public int dwX;
      public int dwY;
      public int dwXSize;
      public int dwYSize;
      public int dwXCountChars;
      public int dwYCountChars;
      public int dwFillAttribute;
      public int dwFlags;
      public short wShowWindow;
      public short cbReserved2;
      public IntPtr lpReserved2;
      public IntPtr hStdInput;
      public IntPtr hStdOutput;
      public IntPtr hStdError;
   }
   #endregion

   #region Constants
   /// <summary>
   /// Size of buffer used when retrieving window names.
   /// </summary>
   public const int MaxWindowNameLength = 100;

   //
   // winAPI constants.
   //
   private const short SW_HIDE = 0;
   private const short SW_NORMAL = 1;
   private const int STARTF_USESTDHANDLES = 0x00000100;
   private const int STARTF_USESHOWWINDOW = 0x00000001;
   private const int UOI_NAME = 2;
   private const int STARTF_USEPOSITION = 0x00000004;
   private const int NORMAL_PRIORITY_CLASS = 0x00000020;
   private const long DESKTOP_CREATEWINDOW = 0x0002L;
   private const long DESKTOP_ENUMERATE = 0x0040L;
   private const long DESKTOP_WRITEOBJECTS = 0x0080L;
   private const long DESKTOP_SWITCHDESKTOP = 0x0100L;
   private const long DESKTOP_CREATEMENU = 0x0004L;
   private const long DESKTOP_HOOKCONTROL = 0x0008L;
   private const long DESKTOP_READOBJECTS = 0x0001L;
   private const long DESKTOP_JOURNALRECORD = 0x0010L;
   private const long DESKTOP_JOURNALPLAYBACK = 0x0020L;
   private const long AccessRights = DESKTOP_JOURNALRECORD | DESKTOP_JOURNALPLAYBACK | DESKTOP_CREATEWINDOW | DESKTOP_ENUMERATE | DESKTOP_WRITEOBJECTS | DESKTOP_SWITCHDESKTOP | DESKTOP_CREATEMENU | DESKTOP_HOOKCONTROL | DESKTOP_READOBJECTS;
   #endregion

   #region Structures
   /// <summary>
   /// Stores window handles and titles.
   /// </summary>
   public struct Window
   {
      #region Private Variables
      private IntPtr m_handle;
      private string m_text;
      #endregion

      #region Public Properties
      /// <summary>
      /// Gets the window handle.
      /// </summary>
      public IntPtr Handle
      {
         get
         {
            return m_handle;
         }
      }

      /// <summary>
      /// Gets teh window title.
      /// </summary>
      public string Text
      {
         get
         {
            return m_text;
         }
      }
      #endregion

      #region Construction
      /// <summary>
      /// Creates a new window object.
      /// </summary>
      /// <param name="handle">Window handle.</param>
      /// <param name="text">Window title.</param>
      public Window(IntPtr handle, string text)
      {
         m_handle = handle;
         m_text = text;
      }
      #endregion
   }
   #endregion

   #region Private Variables
   private IntPtr m_desktop;
   private string m_desktopName;
   private static List<String> m_sc;
   private List<IntPtr> m_windows;
   private bool m_disposed;
   #endregion

   #region Public Properties
   /// <summary>
   /// Gets if a desktop is open.
   /// </summary>
   public bool IsOpen
   {
      get
      {
         return (m_desktop != IntPtr.Zero);
      }
   }

   /// <summary>
   /// Gets the name of the desktop, returns null if no desktop is open.
   /// </summary>
   public string DesktopName
   {
      get
      {
         return m_desktopName;
      }
   }

   /// <summary>
   /// Gets a handle to the desktop, IntPtr.Zero if no desktop open.
   /// </summary>
   public IntPtr DesktopHandle
   {
      get
      {
         return m_desktop;
      }
   }

   /// <summary>
   /// Opens the default desktop.
   /// </summary>
   public static readonly Desktop Default = Desktop.OpenDefault();

   /// <summary>
   /// Opens the desktop the user if viewing.
   /// </summary>
   public static readonly Desktop Input = Desktop.OpenInput();
   #endregion

   #region Construction/Destruction
   /// <summary>
   /// Creates a new Desktop object.
   /// </summary>
   public Desktop()
   {
      // init variables.
      m_desktop = IntPtr.Zero;
      m_desktopName = String.Empty;
      m_windows = new List<IntPtr>();
      m_disposed = false;
   }
   
   /// <summary>
   /// Creates a new Desktop object.
   /// </summary>
   public Desktop(string name)
   {
      // init variables.
      m_desktop = IntPtr.Zero;
      m_desktopName = name;
      m_windows = new List<IntPtr>();
      m_disposed = false;
   }

   // constructor is private to prevent invalid handles being passed to it.
   private Desktop(IntPtr desktop)
   {
      // init variables.
      m_desktop = desktop;
      m_desktopName = Desktop.GetName(desktop);
      m_windows = new List<IntPtr>();
      m_disposed = false;
   }

   ~Desktop()
   {
      // clean up, close the desktop.
      Close();
   }
   #endregion

   #region Methods

   
   /// <summary>
   /// Closes the handle to a desktop.
   /// </summary>
   /// <returns>True if an open handle was successfully closed.</returns>
   public bool Close()
   {
      // make sure object isnt disposed.
      CheckDisposed();

      // check there is a desktop open.
      if (m_desktop != IntPtr.Zero)
      {
         // close the desktop.
         bool result = CloseDesktop(m_desktop);

         if (result)
         {
            m_desktop = IntPtr.Zero;

            m_desktopName = String.Empty;
         }

         return result;
      }

      // no desktop was open, so desktop is closed.
      return true;
   }

   /// <summary>
   /// Opens a desktop.
   /// </summary>
   /// <param name="name">The name of the desktop to open.</param>
   /// <returns>True if the desktop was successfully opened.</returns>
   public bool Open()
   {
      // make sure object isnt disposed.
      CheckDisposed();

      // close the open desktop.
      if (m_desktop != IntPtr.Zero)
      {
         // attempt to close the desktop.
         if (!Close()) return false;
      }

      // open the desktop.
      m_desktop = OpenDesktop(m_desktopName, 0, true, AccessRights);

      // something went wrong.
      if (m_desktop == IntPtr.Zero) return false;

      return true;
   }

   /// <summary>
   /// Switches input to the currently opened desktop.
   /// </summary>
   /// <returns>True if desktops were successfully switched.</returns>
   public bool Show()
   {
      // make sure object isnt disposed.
      CheckDisposed();

      // make sure there is a desktop to open.
      if (m_desktop == IntPtr.Zero) return false;

      // attempt to switch desktops.
      bool result = SwitchDesktop(m_desktop);

      return result;
   }

   /// <summary>
   /// Enumerates the windows on a desktop.
   /// </summary>
   /// <param name="windows">Array of Desktop.Window objects to recieve windows.</param>
   /// <returns>A window colleciton if successful, otherwise null.</returns>
   public List<Window> GetWindows()
   {
      // make sure object isnt disposed.
      CheckDisposed();

      // make sure a desktop is open.
      if (!IsOpen) return null;

      // init the List.
      m_windows.Clear();
      List<Window> windows = new List<Window>();

      // get windows.
      bool result = EnumDesktopWindows(m_desktop, new EnumDesktopWindowsProc(DesktopWindowsProc), IntPtr.Zero);

      // check for error.
      if (!result) return null;

      // get window names.
      IntPtr ptr = Marshal.AllocHGlobal(MaxWindowNameLength);

      foreach(IntPtr wnd in m_windows)
      {
         GetWindowText(wnd, ptr, MaxWindowNameLength);
         windows.Add(new Window(wnd, Marshal.PtrToStringAnsi(ptr)));
      }

      Marshal.FreeHGlobal(ptr);

      return windows;
   }

   private bool DesktopWindowsProc(IntPtr wndHandle, IntPtr lParam)
   {
      // add window handle to colleciton.
      m_windows.Add(wndHandle);

      return true;
   }

   /// <summary>
   /// Creates a new process in a desktop.
   /// </summary>
   /// <param name="path">Path to application.</param>
   /// <returns>The process object for the newly created process.</returns>
   public Process CreateProcess(string path)
   {
      return CreateProcess(path, null);
   }
   
   /// <summary>
   /// Creates a new process in a desktop.
   /// </summary>
   /// <param name="path">Path to application.</param>
   /// <param name="commandLineParameters">Arguments for the application.</param>
   /// <returns>The process object for the newly created process.</returns>
   public Process CreateProcess(string path, string commandLineParameters)
   {
      // make sure object isnt disposed.
      CheckDisposed();
      return Desktop.CreateProcess(path,commandLineParameters,m_desktopName);
   }

   /// <summary>
   /// Prepares a desktop for use by launching the Explorer Shell.  For use only on newly created desktops, call straight after CreateDesktop.
   /// </summary>
   public void Prepare()
   {
      // make sure object isnt disposed.
      CheckDisposed();

      // make sure a desktop is open.
      if (IsOpen)
      {
         // load explorer.
         CreateProcess("explorer.exe");
      }
   }
   
   /// <summary>
   /// Gets an array of all the processes running on this desktop.
   /// </summary>
   /// <returns>An array of the processes.</returns>
   public Process[] GetProcesses()
   {
      return GetProcesses( m_desktopName, StringComparison.InvariantCulture);
   }
   #endregion

   #region Static Methods
   /// <summary>
   /// Enumerates all of the desktops.
   /// </summary>
   /// <param name="desktops">String array to recieve desktop names.</param>
   /// <returns>True if desktop names were successfully enumerated.</returns>
   public static string[] GetDesktops()
   {
      // attempt to enum desktops.
      IntPtr windowStation = GetProcessWindowStation();

      // check we got a valid handle.
      if (windowStation == IntPtr.Zero) return new string[0];

      string[] desktops;

      // lock the object. thread safety and all.
      lock(m_sc = new List<String>())
      {
         bool result = EnumDesktops(windowStation, new EnumDesktopProc(DesktopProc), IntPtr.Zero);

         // something went wrong.
         if (!result) return new string[0];

         //	// turn the collection into an array.
         desktops = new string[m_sc.Count];
         for(int i = 0; i < desktops.Length; i++) desktops[i] = m_sc[i];
      }

      return desktops;
   }

   private static bool DesktopProc(string lpszDesktop, IntPtr lParam)
   {
      // add the desktop to the collection.
      m_sc.Add(lpszDesktop);

      return true;
   }

   /// <summary>
   /// Switches to the specified desktop.
   /// </summary>
   /// <param name="name">Name of desktop to switch input to.</param>
   /// <returns>True if desktops were successfully switched.</returns>
   public static bool Show(string name)
   {
      // attmempt to open desktop.
      bool result = false;

      using (Desktop d = new Desktop(name))
      {
         result = d.Open();

         // something went wrong.
         if (!result) return false;

         // attempt to switch desktops.
         result = d.Show();
      }

      return result;
   }

   /// <summary>
   /// Gets the desktop of the calling thread.
   /// </summary>
   /// <returns>Returns a Desktop object for the valling thread.</returns>
   public static Desktop GetCurrent()
   {
      // get the desktop.
      return new Desktop(GetThreadDesktop(System.Threading.Thread.CurrentThread.ManagedThreadId));
   }

   /// <summary>
   /// Sets the desktop of the calling thread.
   /// NOTE: Function will fail if thread has hooks or windows in the current desktop.
   /// </summary>
   /// <param name="desktop">Desktop to put the thread in.</param>
   /// <returns>True if the threads desktop was successfully changed.</returns>
   public static bool SetCurrent(Desktop desktop)
   {
      // set threads desktop.
      if (!desktop.IsOpen) return false;
      return SetThreadDesktop(desktop.DesktopHandle);
   }

   /// <summary>
   /// Opens a desktop.
   /// </summary>
   /// <param name="name">The name of the desktop to open.</param>
   /// <returns>If successful, a Desktop object, otherwise, null.</returns>
   public static Desktop Open(string name)
   {
      // open the desktop.
      Desktop desktop = new Desktop(name);
      bool result = desktop.Open();

      // something went wrong.
      if (!result) return null;

      return desktop;
   }

   /// <summary>
   /// Opens the current input desktop.
   /// </summary>
   /// <returns>If successful, a Desktop object, otherwise, null.</returns>
   public static Desktop OpenInput()
   {
      // open the desktop.         
      IntPtr deskptr = OpenInputDesktop(0, true, AccessRights);
      if (deskptr == IntPtr.Zero) return null;
      
      return new Desktop(deskptr);
   }

   /// <summary>
   /// Opens the default desktop.
   /// </summary>
   /// <returns>If successful, a Desktop object, otherwise, null.</returns>
   public static Desktop OpenDefault()
   {
      // opens the default desktop.
      return Desktop.Open("Default");
   }

   /// <summary>
   /// Creates a new desktop.
   /// </summary>
   /// <param name="name">The name of the desktop to create.  Names are case sensitive.</param>
   /// <returns>If successful, a Desktop object, otherwise, null.</returns>
   public static Desktop Create(string name)
   {
      // make sure desktop doesnt already exist.
      if (Desktop.Exists(name))
      {
         // it exists, so open it.
         return Open(name);
      }

      // attempt to create desktop.
      IntPtr deskptr = CreateDesktop(name, IntPtr.Zero, IntPtr.Zero, 0, AccessRights, IntPtr.Zero);
      if (deskptr == IntPtr.Zero) return null;

      // open the desktop.
      return Open(name);
   }

   /// <summary>
   /// Gets the name of a given desktop.
   /// </summary>
   /// <param name="desktop">Desktop object whos name is to be found.</param>
   /// <returns>If successful, the desktop name, otherwise, null.</returns>
   public static string GetName(Desktop desktop)
   {
      // get name.
      if (desktop.IsOpen) return null;

      return GetName(desktop.DesktopHandle);
   }

   
   public static Win32Exception LastError;
   
   /// <summary>
   /// Gets the name of a desktop from a desktop handle.
   /// </summary>
   /// <param name="desktopHandle"></param>
   /// <returns>If successful, the desktop name, otherwise, null.</returns>
   public static string GetName(IntPtr desktopHandle)
   {
      // check its not a null pointer.
      // null pointers wont work.
      if (desktopHandle == IntPtr.Zero) return null;

      // get the length of the name.
      int needed = 0;
      string name = null;
      // always returns false, because we pass 0 for available size
      GetUserObjectInformation(desktopHandle, UOI_NAME, IntPtr.Zero, 0, ref needed);

      // get the name.
      IntPtr ptr = Marshal.AllocHGlobal(needed);
      if(!GetUserObjectInformation(desktopHandle, UOI_NAME, ptr, needed, ref needed)) {
         Marshal.FreeHGlobal(ptr);
         LastError = new Win32Exception();
      } else {
         name = Marshal.PtrToStringAnsi(ptr);
         Marshal.FreeHGlobal(ptr);
      }
      return name;
   }

   /// <summary>
   /// Checks if the specified desktop exists (using a case sensitive search).
   /// </summary>
   /// <param name="name">The name of the desktop.</param>
   /// <returns>True if the desktop exists, otherwise false.</returns>
   public static bool Exists(string name)
   {
      return Desktop.Exists(name, StringComparison.InvariantCultureIgnoreCase);
   }

   /// <summary>
   /// Checks if the specified desktop exists.
   /// </summary>
   /// <param name="name">The name of the desktop.</param>
   /// <param name="comparisonType">The type of string comparison to do.</param>
   /// <returns>True if the desktop exists, otherwise false.</returns>
   public static bool Exists(string name, StringComparison comparisonType)
   {
      // enumerate desktops.
      string[] desktops = Desktop.GetDesktops();

      // return true if desktop exists.
      foreach(string desktop in desktops)
      {
         if(desktop.Equals( name, comparisonType )) return true;
      }

      return false;
   }

   /// <summary>
   /// Creates a new process on the specified desktop.
   /// </summary>
   /// <param name="path">Path to application.</param>
   /// <param name="commandLineParameters">Arguments for the application.</param>
   /// <param name="desktop">Desktop name.</param>
   /// <returns>A Process object for the newly created process, otherwise, null.</returns>
   public static Process CreateProcess(string path, string commandLineParameters, string desktop)
   {
      if (!Desktop.Exists(desktop)) return null;

      // set startup parameters.
      STARTUPINFO si = new STARTUPINFO();
      si.cb = Marshal.SizeOf(si);
      si.lpDesktop = desktop;

      PROCESS_INFORMATION pi = new PROCESS_INFORMATION();

      //StringBuilder lpPath = new StringBuilder(path);
      StringBuilder lpCommandLine = new StringBuilder();
      lpCommandLine.Append("\"");
      lpCommandLine.Append(path);
      lpCommandLine.Append("\" ");
      lpCommandLine.Append(commandLineParameters);
      // lpPath.EnsureCapacity(256);
      // create the process.
      if(!CreateProcess(null, lpCommandLine.ToString(), IntPtr.Zero, IntPtr.Zero, true, NORMAL_PRIORITY_CLASS, IntPtr.Zero, null, ref si, out pi) ) {
         throw new Win32Exception();
      }
      
      // Get the process.
      return Process.GetProcessById(pi.dwProcessId);
      
   }


   
   /// <summary>
   /// Gets an array of all the processes running on the Input desktop.
   /// </summary>
   /// <returns>An array of the processes.</returns>
   public static Process[] GetInputProcesses()
   {
      return GetProcesses( GetName(Desktop.Input.DesktopHandle), StringComparison.InvariantCulture);
   }  
   
   /// <summary>
   /// Gets an array of all the processes running on the specified desktop.
   /// </summary>
   /// <param name="desktop">The name of the desktop for which to return processes</param>
   /// <returns>An array of the processes.</returns>
   public static Process[] GetProcesses(string desktop)
   {
      return GetProcesses( desktop, StringComparison.InvariantCultureIgnoreCase);
   }      
   
   /// <summary>
   /// Gets an array of all the processes running on the specified desktop (using the speficied string comparison)
   /// </summary>
   /// <param name="desktop">The name of the desktop for which to return processes</param>
   /// <param name="comparisonType">The type of string comparison to do</param>
   /// <returns>An array of the processes.</returns>
   public static Process[] GetProcesses(string desktop, StringComparison comparisonType)
   {
      // get all processes.
      Process[] processes = Process.GetProcesses();

      List<Process> procs = new List<Process>();

      // cycle through the processes.
      foreach(Process process in processes)
      {
         // check the threads of the process - are they in this one?
         foreach(ProcessThread pt in process.Threads)
         {
            string deskname = GetName(GetThreadDesktop(pt.Id));
            if(deskname == null) continue;
            
            // check for a desktop name match.
            if (deskname.Equals(desktop,comparisonType))
            {
               // found a match, add to list, and bail.
               procs.Add(process);
               break;
            } else {
               Console.WriteLine("Wow, Really? The '" + deskname + "' desktop showed up!");
            }
         }
      }
      return procs.ToArray();
   }
   #endregion

   #region IDisposable
   /// <summary>
   /// Dispose Object.
   /// </summary>
   public void Dispose()
   {
      // dispose
      Dispose(true);

      // suppress finalisation
      GC.SuppressFinalize(this);
   }

   /// <summary>
   /// Dispose Object.
   /// </summary>
   /// <param name="disposing">True to dispose managed resources.</param>
   public virtual void Dispose(bool disposing)
   {
      if (!m_disposed)
      {
         // dispose of managed resources,
         // close handles
         Close();
      }

      m_disposed = true;
   }

   private void CheckDisposed()
   {
      // check if disposed
      if (m_disposed)
      {
         // object disposed, throw exception
         throw new ObjectDisposedException("");
      }
   }
   #endregion

   #region ICloneable
   /// <summary>
   /// Creates a new Desktop object with the same desktop open.
   /// </summary>
   /// <returns>Cloned desktop object.</returns>
   public object Clone()
   {
      // make sure object isnt disposed.
      CheckDisposed();

      Desktop desktop = new Desktop(m_desktopName);

      // if a desktop is open, make the clone open it.
      if (IsOpen) desktop.Open();

      return desktop;
   }
   #endregion

   #region Overrides
   /// <summary>
   /// Gets the desktop name.
   /// </summary>
   /// <returns>The desktop name, or a blank string if no desktop open.</returns>
   public override string ToString()
   {
      // return the desktop name.
      return m_desktopName;
   }
   #endregion
}