title: How to determine whether or not the component is destroyed?
body: <p>I made this declaration: <code>private...T:TTimer</code>
  Now when I free <code>T</code> after creation the pointer still remains for sure, but as long as the target object is destroyed, any operation on this pointer may cause <code>Invalida Pointer Operation</code> so I just want to know whether or not the target object is destroyed. How can I do this?
  (I don't want to use <code>FreeAndNil</code>)</p>