delphi Button1.Down 另外用法

var

  i: integer;

begin

  i := 0;

  while (SpeedButton1.Down) and (i < 500) do

  begin

    Memo1.Lines.Insert(0, 'on ' + i.tostring);

    inc(i);

    Application.ProcessMessages;

  end;

  if not(SpeedButton1.Down) then

    Memo1.Lines.Insert(0, 'off')

end;