{Code for Unit1}

const

 UM_MyGlobalMessage = WM_USER + 1;

type

 TForm1 = class(TForm)

  Label1: TLabel;

  Button1: TButton;

  procedure FormShow(Sender: TObject);

  procedure Button1Click(Sender: TObject);

 private

 {Private declarations}

  procedure UMMyGlobalMessage(var AMessage: TMessage); message

  UM_MyGlobalMessage;

 public

 {Public declarations}

 end;

var

 Form1: TForm1;

implementation

{$R *.DFM}

uses Unit2;

procedure TForm1.FormShow(Sender: TObject);

begin

 Form2.Show;

end;

procedure TForm1.UMMyGlobalMessage(var AMessage: TMessage);

begin

 Label1.Left := AMessage.WParam;

 Label1. := AMessage.LParam;

 Form1.Caption := 'Got It!';

end;

procedure TForm1.Button1Click(Sender: TObject);

var

 f: integer;

begin

 for f := 0 to Screen.FormCount - 1 do

  Screen.Forms[f].Perform(UM_MyGlobalMessage, 42, 42);

end;

{Code for Unit2}

const

 UM_MyGlobalMessage = WM_USER + 1;

type

 TForm2 = class(TForm)

  Label1: TLabel;

 private

 {Private declarations}

  procedure UMMyGlobalMessage(var AMessage: TMessage);

  message UM_MyGlobalMessage;

 public

 {Public declarations}

 end;

var

 Form2: TForm2;

implementation

{$R *.DFM}

procedure TForm2.UMMyGlobalMessage(var AMessage: TMessage);

begin

 Label1.Left := AMessage.WParam;

 Label1. := AMessage.LParam;

 Form2.Caption := 'Got It!';

end;