problem in using CPaintDC

Hi

I am trying to change a piece of code that ran in CClientDC into
CPaintDC on VC 6.

I have tried using ...

//win32 app
// needs multi threading

#include <afxwin.h>
#include <afx.h>

class A_Std_Window :public CFrameWnd
{
    CPoint m_StartPoint, m_EndPoint;
    public:
    A_Std_Window()
    {
         Create(NULL,"put window title here");
    }
    void OnLButtonUp();
    DECLARE_MESSAGE_MAP()
};

BEGIN_MESSAGE_MAP( A_Std_Window, CFrameWnd)
    ON_WM_LBUTTONUP() //Macro to map the left button click to the
handler
END_MESSAGE_MAP()

void A_Std_Window::OnLButtonUp()
{
     // TODO: Add your message handler code here and/or call default

    m_StartPoint.x=40;
    m_StartPoint.y=50;

  m_EndPoint.x=4;
    m_EndPoint.y=5;

    CPaintDC dc(this); //paint here

    dc.MoveTo(m_StartPoint);
    dc.LineTo(m_EndPoint);

    dc.FillSolidRect(0,0,40,40, RGB(255,0,0));
}

class MyApp :public CWinApp
{
     A_Std_Window *windo; // create a window pointer
     public:
     BOOL InitInstance()
     {
           windo = new A_Std_Window();
           m_pMainWnd = windo;
           m_pMainWnd->ShowWindow(1);
           return 1;
      }
};

MyApp theApp;

.....
It compiles but does exactly nothing

Could someone please tell me what I am doing wrong

Thanks
Bruce