nbsp; Button1.Enabled := FALSE;
  StatusBar1.SimpleText := ''Now waiting for a filename change'';
  Application.ProcessMessages;
  {enter the loop}
  while Waiting do
  begin
    {at this point, the application is suspended until the notification
     object is signaled that a filename change has occured in the
     selected directory (this includes file deletions)}
    dwResult := WaitForSingleObject(NotificationHandle,INFINITE);
    if (dwResult = WAIT_OBJECT_0) then

    begin
      {indicate that the notification object was signaled}
      ShowMessage(''The selected directory signaled a filename change'');

      {query the user to see if they wish to continue monitoring this
       directory}
      if Application.MessageBox(''Do you wish to continue monitoring this directory?'', ''Continue?'', MB_ICONQUESTION or
                                MB_YESNO) = IDYES then

        {if the user wishes to continue monitoring the directory, reset
         the notification object and continue the loop}
        FindNextChangeNotification(NotificationHandle)
      else
        {otherwise break out of the loop}
        Waiting := FALSE;
    end;
  end;

  {close the notification object}
  FindCloseChangeNotification(NotificationHandle);

  {reset UI elements}

  Button1.Enabled := FALSE;
  Button2.Enabled := TRUE;
  StatusBar1.SimpleText := '''';
  FileListBox1.Update;
end;
===========================================
下面是一个监视的控件：
unit dirnotify;

interface

uses
  Windows, Messages, SysUtils, Classes,
  Graphics, Controls, Forms, Dialogs;

type
  EDirNotificationError = class(Exception);

  TDirNotify = class;
  TNotifyFilter = (nfFileName, nfDirName, nfAttributes, nfSize, nfLastWrite,
    nfSecurity);
  TNotifyFilters = set of TNotifyFilter;

  TNotificationThread = class(TThread)
    Owner: TDirNotify;
    procedure Execute; override;
    procedure DoChange;
  end;

  TDirNotify = class(TComponent)
  private
    FEnabled: Boolean;
 &n