CRect(0,0,0,0)//这是多大啊??????

m_Thumb.Create(WS_CHILD | WS_VISIBLE, this, 0);


BOOL CBitWnd::Create(UINT wStyle, CWnd * pParentWnd, UINT nID)
{
LPCTSTRlpWndName = NULL;
lpWndName = AfxRegisterWndClass(CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW,
AfxGetApp()->LoadStandardCursor(IDC_ARROW),
(HBRUSH)GetStockObject(BLACK_BRUSH), NULL);
if( lpWndName == NULL )
return FALSE;
//
// 2.0 Create the window directly...
//wStyle |= WS_CLIPCHILDREN | WS_CLIPSIBLINGS;
return CWnd::Create(lpWndName, NULL, wStyle, CRect(0, 0, 0, 0), pParentWnd, nID);
}

[解决办法]
就是生成一个位置、长和宽都是0的CRect类对象
[解决办法]
等于就是看不到这个UI对象