CWnd实现拖动框，鼠标拖动时CWnd闪烁

maoxk

在鼠标移动事件中改变CWnd大小，大小改变时CWnd窗口会闪烁，
重载CWnd类的OnEraseBkgnd方法返回TRUE、重载CWnd 的 OnPaint使用双缓冲不能解决问题

在  CMFCApplication1Dlg  类中声明
MyWnd    *m_pwnd;
CPoint    m_firstpos;
成员

BOOL CMFCApplication1Dlg::OnInitDialog()
{
RECT rect;
        rect.top = 0;
        rect.left = 0;
        rect.right = 1;
        rect.bottom = 1;
        m_pwnd = new CWnd;
        BOOL b = m_pwnd->Create(NULL, NULL, WS_BORDER | WS_CHILD, rect, this,  123);
        m_pwnd->SetParent(this);
        m_pwnd->SetWindowPos(&wndTopMost,0,0,0,0,SWP_NOSIZE|SWP_NOMOVE);
}

void CMFCApplication1Dlg::OnLButtonDown(UINT nFlags, CPoint point)
{
        m_firstpos = point;
        CDialogEx::OnLButtonDown(nFlags, point);
}
void CMFCApplication1Dlg::OnMouseMove(UINT nFlags, CPoint point)
{
        RECT rc;
        rc.top = m_firstpos.y;
        rc.left = m_firstpos.x;
        rc.right = point.x - 2;
        rc.bottom = point.y -2;
        m_pwnd->MoveWindow(&rc);
        m_pwnd->Invalidate(1);
        m_pwnd->ShowWindow(SW_SHOW);

        CDialogEx::OnMouseMove(nFlags, point);
}