title: How to implement custom TGraphicControl.OnResize?
body: <p>Should I use <code>WM_WINDOWPOSCHANGED;</code>? (I havn't seen <code>CM_WINDOWPOSCHANGED</code> or similar)</p>
  
  <p>Will the TGraphicControl even be notified of this message (it has no Handle)? What is the correct method?</p>
  
  <p>Thanks.</p>
  
  <hr>
  
  <p>Just a thoght after accepting the answer:</p>
  
  <p>Strangely or maybe intentionally <code>OnResize</code> fires even if only the Top/Left of the control position where changed:<br>
  in Delphi 7 <code>Resize</code> is called in <code>TControl.SetBounds</code> right after it calls <code>Perform(WM_WINDOWPOSCHANGED)</code> even if no actual resize was made and the control was moved.<br>
  Is this by design? </p>