title: How to add a property to TTabSheet such that it can be used at design time with TPageControl
body: <p>I would like to add "MyProperty" to TTabSheet and work with it at design time. However if I subclass it I fear I will need to also subclass TPageControl, since it internally creates/manages the TTabSheets.  </p>
  
  <p>I believe this would require duplicating the TTabSheet management code to reference TMyTabSheet instead of TTabSheet, since it will need to invoke TMyTabSheet.create.  This feels like something I will regret when a new version of Delphi updates TPageControl and I forget to update TMyPageControl.</p>
  
  <p>I am also researching "class helpers" as another option.</p>
  
  <p>Does anyone have advice on how to best accomplish this?</p>
  
  <p>Thanks!</p>