Minimise Delphi Application to System Tray

A short code snippet which will allow a program icon to be displayed in the application to system tray when the form is minimised.

unit Unit1;

interface

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

const
  WM_NOTIFYICON  = WM_USER+333;

type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    { Private declarations }
    tnid: TNotifyIconData;
    HMainIcon: HICON;
    procedure CMClickIcon(var msg: TMessage); message WM_NOTIFYICON;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.CMClickIcon(var msg: TMessage);
begin
  case msg.lparam of
    WM_LBUTTONDBLCLK : Show;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  HMainIcon                := LoadIcon(MainInstance, 'MAINICON');

  Shell_NotifyIcon(NIM_DELETE, @tnid);

  tnid.cbSize              := sizeof(TNotifyIconData);
  tnid.Wnd                 := handle;
  tnid.uID                 := 123;
  tnid.uFlags              := NIF_MESSAGE or NIF_ICON or NIF_TIP;
  tnid.uCallbackMessage    := WM_NOTIFYICON;
  tnid.hIcon               := HMainIcon;
  tnid.szTip               := 'POP3 Server';

  Shell_NotifyIcon(NIM_ADD, @tnid);
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  Action := caNone;
  Hide;
end;

/If desired, you can tell Delphi not to show the mainform by adding to the
/'Project source' the line
/  Application.ShowMainForm := False;

/(Credits for this go to Peter Remeijer)

end.