Controls in the Dockpane disappeared

I have attached a CDialog as DockingPane in my  no-doc/view application,
but when mouse move on the autoHide  or close button of the pane, the all of controls in the CDialog are disappeared.
otherwise . when i resizeing the pane ,the CDialog is flicker endlessly .
some of code in the following
=======================================
BOOL CMainFrame::PreCreateWindow(CREATESTRUCT& cs)
{
 if( !CFrameWnd::PreCreateWindow(cs) )
  return FALSE;
 // TODO: Modify the Window class or styles here by modifying
 //  the CREATESTRUCT cs

 cs.style |= WS_CLIPCHILDREN|WS_CLIPSIBLINGS;
 return TRUE;
}

CXTPOfficeBorder<CReportFilesPane>m_wndFiles;
ps:  CReportFilesPane is  derived CDialog 

LRESULT CMainFrame::OnDockingPaneNotify(WPARAM wParam, LPARAM lParam)
{
 .......
 if (m_wndFiles.GetSafeHwnd() == 0)
 {     
  m_wndFiles.Create(IDD_REPORT_FILESDLG,this);
 }      
 pPane->Attach(&m_wndFiles);
 .......

}

==================================
i am not sure that  is the problem about WS_CLIPCHILDREN and WS_CLIPSIBLINGS.  so add the following code.
but it's not any change.
BOOL CReportFilesPane::PreCreateWindow(CREATESTRUCT& cs)
{

 if( !CDialog::PreCreateWindow(cs) )
  return FALSE;
 cs.style = WS_CLIPCHILDREN|WS_CLIPSIBLINGS;

 return TRUE;
 
}

how to does i.

thanks
deepstar

hi. oleg　
this following code is in my CChildview ,and the CChildview is derived CWnd, however  The problem is still unsolved
BOOL CChildView::PreCreateWindow(CREATESTRUCT& cs)
{
 // TODO: Modify the Window class or styles here by modifying
 //  the CREATESTRUCT cs
 if( !CWnd::PreCreateWindow(cs) )
  return FALSE;
 cs.style |= WS_CLIPCHILDREN|WS_CLIPSIBLINGS;
 return TRUE;
} this is normal pic

Hi;

How did you solve this?