pb：

  string ls_Classname,ls_WindowName
    ulong ll_winhandle
  uint  li_result
    setnull(ls_ClassName)
    ls_WindowName ="Form1" //delphi程序窗口名稱
    ll_winhandle = findwindow(ls_ClassName,ls_WindowName)

if ll_winhandle>0 then //撥通
  li_result = RegisterWindowMessage('1111') //注冊系統消息，返回系統唯一消息號

  post(ll_winhandle,li_result,0,0)
  messagebox("提示","知道")
else
 messagebox("提示","沒有找到")
end if

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delphi：

聲明部分：

PRivate
    Msg: LongInt;
    hWndC : THandle;
    { Private declarations }
  protected
    procedure WndProc(var Message: TMessage); override;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Msg := RegisterWindowMessage('1111');//返回系統唯一消息號，1111為自定義消息內容
  Self.BringToFront;

end;

procedure TForm1.WndProc(var Message: TMessage);
 var
   mypt:Tpoint;
   s:string;
begin

  if Message.msg = msg then begin
      ShowMessage(inttostr(message.lparam) );
     end ;

    inherited;
 end;