CXTPDockingPane - some questions

// DockPaneWnd.h : main header file for the SAMPLEAPP application
//
#if !defined(__DOCKPANEWND_H__)
#define __DOCKPANEWND_H__
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
template<class BASE_CLASS>
        class CDockPaneWnd : public BASE_CLASS
{
protected:
    virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
    {
        switch (message)
        {
              case WM_CREATE:
              {
                  if (BASE_CLASS::WindowProc(message, wParam, lParam) == -1)
                            return -1;
                  SetFont(CXTPPaintManager::GetRegularFont());
                  return 0;
              }
              case WM_NCPAINT:
              {
                  CWindowDC dc(this);
                  CRect rc;
                  GetWindowRect(&rc);
                  int cx = rc.Width();
                  int cy = rc.Height();
                  const COLORREF clrFrame =  GetXtremeColor(XPCOLOR_3DSHADOW);
                  dc.Draw3dRect(0, 0, cx, cy, clrFrame, clrFrame);
                  return TRUE;
              }
              case WM_NCCALCSIZE:
              {
                  NCCALCSIZE_PARAMS FAR* lpncsp = (NCCALCSIZE_PARAMS FAR*)lParam;
                  // adjust non-client area for border space
                  lpncsp->rgrc[0].left   += 1;
                  lpncsp->rgrc[0].top    += 1;
                  lpncsp->rgrc[0].right  -= 1;
                  lpncsp->rgrc[0].bottom -= 1;
                  return TRUE;
              }
        }
        return BASE_CLASS::WindowProc(message, wParam, lParam);
    }
};

 //////////////////////////////////////////////////////////// /////////////////
//{{AFX_INSERT_LOCATION}}
    // Microsoft Visual C++ will insert additional declarations immediately before the previous line.
#endif // !defined(__DOCKPANEWND_H__)

               case IDR_PANE_CUSTOM :
                       if (m_wndCustomPane.GetSafeHwnd() == 0)
                       {
                           m_wndCustomPane.Create(NULL, NULL, WS_CHILD|WS_CLIPCHILDREN|WS_CLIPSIBLINGS, CRect(0,0,0,0), this, 0);
                       }
                       pPane->Attach(&m_wndCustomPane);
                       break;