立即给分哦！！！窗口为什么只是闪一下后消失了？

下面是程序代码：不知道为什么？窗口不能正常显示？


#include <Afxwin.h>

#define IDC_SCROLLBAR 100
#define MIN_RANGE 0
#define MAX_RANGE 100

class CTestApp:public CWinApp
{
public:
virtual BOOL InitInstance();
};

CTestApp TestApp;

class CTestWnd:public CFrameWnd
{
CScrollBar *sb;
public:
CTestWnd();
afx_msg void OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar );
DECLARE_MESSAGE_MAP()
};


BEGIN_MESSAGE_MAP(CTestWnd,CFrameWnd)
ON_WM_HSCROLL()
END_MESSAGE_MAP()

CTestWnd::CTestWnd()
{
CRect r;
Create(NULL,"Test Windows",WS_OVERLAPPEDWINDOW,CRect(0,0,200,200));
GetClientRect(&r);
sb=new CScrollBar();
sb->Create(WS_CHILD|WS_VISIBLE|SBS_HORZ,CRect(10,10,r.Width()-10,30),this,IDC_SCROLLBAR);
sb->SetScrollRange(MIN_RANGE,MAX_RANGE,TRUE);
}

void CTestWnd::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar )
{
int pos;
pos=sb->GetScrollPos();
switch(nSBCode)
{
case SB_LINEUP:
pos-=1;
break;
case SB_LINEDOWN:
pos+=1;
break;
case SB_PAGEUP:
pos-=10;
break;
case SB_PAGEDOWN:
pos+=10;
break;
case SB_BOTTOM:
pos=MAX_RANGE;
break;
case SB_TOP:
pos=MIN_RANGE;
break;
case SB_THUMBPOSITION:
pos=nPos;
break;
default: return;
}
if(pos<MIN_RANGE)
pos=MIN_RANGE;
else if(pos>MAX_RANGE)
pos=MAX_RANGE;
sb->SetScrollPos(pos,TRUE);
}

BOOL CTestApp::InitInstance()
{
CTestWnd *m_pWindow=new CTestWnd();
m_pWindow->ShowWindow(SW_SHOW);
m_pWindow->UpdateWindow();
return TRUE;
}