mfc绘制框选边框
CPen penBlack(PS_SOLID, 1, CLR_BK), penWhite(PS_DOT, 1, RGB(255, 255, 255)), *pOldPen;
CBrush brush, *pOldBrh;
brush.CreateStockObject(NULL_BRUSH);
pOldBrh = (CBrush*)pDC->SelectObject(&brush);
pOldPen = (CPen *)pDC->SelectObject(&penBlack);
pDC->Rectangle(m_rtBoxSel);
pDC->SelectObject(&penWhite);
pDC->Rectangle(m_rtBoxSel);
pDC->SelectObject(pOldPen);
pDC->SelectObject(pOldBrh);
效果：