title: TVN_SELCHANGING not received
body: <p>I have a WTL81 app. CMainFrame has a child CPaneContainer, that has a child window CTreeViewCtrl. The problem is CTreeViewCtrl doesn't receive TVN_SELCHANGING message. </p>
  
  <p>I have "spied" CTreeViewCtrl and his parent (CPaneContainer) and no notification code is received. </p>
  
  <p>CMainFrame is implemented from public <code>CFrameWindowImpl&lt;CMainFrame&gt;</code></p>
  
  <p>CPaneContainer is implemented like this</p>
  
  <pre><code>class PaneContainerReflectNotif : public CPaneContainer 
  {
      BEGIN_MSG_MAP(PaneContainerReflectNotif)
          CHAIN_MSG_MAP(CPaneContainer)
          REFLECT_NOTIFICATIONS()
      END_MSG_MAP()
  };
  </code></pre>
  
  <p>Tree is implemented like this</p>
  
  <pre><code>class MyTreeView : 
      public CWindowImpl&lt;CatalogTreeView, CTreeViewCtrl&gt;,
      public CCustomDraw&lt;CatalogTreeView&gt;,
      public CTheme
  
     ...
  
  BEGIN_MSG_MAP_EX(MyTreeView )
      MSG_WM_CREATE(OnCreate)
      MSG_WM_DESTROY(OnDestroy)
      REFLECTED_NOTIFY_CODE_HANDLER_EX(NM_DBLCLK, OnDblClick)
      REFLECTED_NOTIFY_CODE_HANDLER_EX(TVN_ITEMEXPANDING, OnItemExpanding)
      REFLECTED_NOTIFY_CODE_HANDLER_EX(TVN_SELCHANGING, OnSelChanged)
  </code></pre>
  
  <p>OnDblClick - <strong>works fine</strong><br>
  OnItemExpanding - <strong>works fine</strong><br>
  OnSelChanged -  <strong>doesn't work</strong>    </p>
  
  <p>any ideas on what could be the problem ?</p>