title: how to get CREATESTRUCT of a window?
body: <p>I am trying to make a windows GUI application.</p>
  
  <p>I declared some static variables in my window procedure function and initialized it in the <code>WM_CREATE</code> whose <code>lParam</code> is a pointer to the <code>CREATESTRUCT</code>. However, since these values are static, I can only make one instance of my window; if I make more the previous instances' data will be changed to the new datas.
  Is there a way to access the <code>CREATESTRUCT</code> of a window after the <code>WM_CREATE</code> message so that I can solve this problem?</p>