title: How to ensure a CPropertyPage has been created BEFORE user clicks on it in a CPropertySheet?
body: <p>I have created a <code>CPropertySheet</code>-based modal dialog in MFC (using BCGSoft classes derived from <code>CPropertySheet</code> / <code>CPropertyPage</code>).  When a user takes a certain action in one of the <code>CPropertyPage</code>'s, I would like to enable/disable a control in a different <code>CPropertyPage</code>.</p>
  
  <p>This works just fine, assuming the user has already clicked on the tab to instantiate the second <code>CPropertyPage</code>.  However, MFC delays the creation of the second <code>CPropertyPage</code> until it is activated by the user.  In this scenario, the control within the second <code>CPropertyPage</code> does not exist, and MFC throws an error.</p>
  
  <p>To overcome this, I would like to ensure that all <code>CPropertyPage</code>'s exist by calling the necessary functions within the <code>CPropertySheet</code> <code>OnInitDialog()</code>.  Can someone please explain how to do this?</p>