modalless Dialog Box Refresh?

I made the openGL viewer by SDI app(MFC)

And I inserted an openGL modalless dialog box.

Here I want to implement that the openGL modalless dialog box is refresh(redrawn)

The code is following…

m_pDlg = new COpenglDlg;
m_pDlg->Create(this);
m_pDlg->ShowWindow(SW_SHOW);

m_pDlg->InvalidateRect(NULL,FALSE);
m_pDlg->UpdateWindow();

But openGL dialog box is not updated…

Why?

Plz help me…