unit Unit1;

interface

uses
  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics,
    Controls, Forms, Dialogs, Menus;

type
  TForm1 = class (TForm)
    procedure FormCreate (Sender: TObject);
  private
  { private declarations }
    public
    procedure WinMsg (var Msg: TMsg; var Handled: Boolean);
    { This is what handles the messages }
    procedure DOWHATEVER;
    { procedure to do whatever }

  end;

var
  Form1 : TForm1;

implementation

{$R *.DFM}
const
  ItemId = 99;

{the ID number for your menu item--can be anything} 
procedure TForm1.WinMsg (var Msg: TMsg; var Handled: Boolean); 
begin 
  if Msg.message = WM_SYSCOMMAND then 
    {if the message is a system one...} 
    if Msg.WPARAM = ItemId then 
      DOWHATEVER 
  {then check if its parameter is your Menu items ID}  
end; 


procedure TForm1.FormCreate (Sender: TObject); 
begin 
  Application.OnMessage := WinMsg; 
  {tell your app that 'winmsg' is the application message handler} 
  AppendMenu (GetSystemMenu (Form1.Handle, False), 
    MF_SEPARATOR, 0, ''); 
  {Add a seperator bar to form1} 
  AppendMenu (GetSystemMenu (Form1.Handle, False), 
    MF_BYPOSITION, ItemId, '&New Item'); 
  {add your menu item to form1} 
  AppendMenu (GetSystemMenu (Application.Handle, False), 
    MF_SEPARATOR, 0, ''); 
  {Add a seperator bar to the application system menu(used }
  {when app is minimized)} 
  AppendMenu (GetSystemMenu (Application.Handle, False), 
    MF_BYPOSITION, ItemId, '&New Item') 
  {add your menu itemto the application system menu(used when app is minimized)} 
  
  { for more information on the AppendMenu and GetSystemMenu see online help} 
end; 


procedure TForm2.DOWHATEVER; 
begin 
  { add whatever you want to this procedure } 
end; 

end.