unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
const
  WM_MY=WM_USER+1;
type
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    procedure my(var MSG:TMSG);message WM_MY;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
sendmessage(handle,WM_MY,100,200);
end;

procedure TForm1.my(var msg:TMSG);
begin
memo1.Lines.Add(inttostr(msg.hwnd ));
memo1.Lines.Add(inttostr(msg.message));
memo1.Lines.Add(inttostr(msg.wParam  ));
memo1.Lines.Add(inttostr(msg.lParam  ));
memo1.Lines.Add(datetimetostr(msg.time ));
memo1.Lines.Add(inttostr(msg.pt.X ));
memo1.Lines.Add(inttostr(msg.pt.y ));
end;

end.
如上,hwnd没有值的,MEMO1中,分别是
1025
100
200
0
5301-9-14
2010220340
786490

为什么会是这样的,并且,如果在两个程序间传递一个结构指针,也无法取得结构的数据?