Trouble with broadcasting messages (TWinControl)

{ Delphi 7 on XP Pro}
Hi,
I am trying to send a custom broadcast message to all components within my application. I can send a custom message using "PostMessage" from within the main form and the forms handler gets it fine. If I try a broadcast the handler doesn't catch it. The Delphi help shows how to send the broadcast message but not how to trap them.  Could someone provide a code snippet to illustrate how to post and catch a custom broadcast  message. Here are some of the key functions from my test program:



const
MY_MESSAGE= WM_USER +5;

private { Form1 }
 procedure MessageHandler(var M: TMessage); message MY_MESSAGE;

{ The message handler for the form }
procedure TForm1.MessageHandler(var M: TMessage);
begin ......

procedure TForm1.FormCreate(Sender: TObject);
var
 Msg:TMessage;
begin
  Msg.Msg := MY_MESSAGE;
  Msg.WParam := 0;
  Msg.LParam := Longint(Self);
  Msg.Result := 0;

  self.Broadcast(Msg); // This doesn't work
//  PostMessage(handle,MY_MESSAGE,0,0); // this does work