常用的Windows消息
ON_WM_CHAR(从键盘输入字符)----void A::OnChar(UINT nChar,UINT nRepCnt,UINT nFlags)
ON_WM_COMMAND(用户选择菜单内的某项,或者是控件给其父类发送了一个通知)
----void A::OnCommand(WPARAMwParam,LPARAM lParam)
ON_WM_CREATE(生成窗口)----void A::OnCreate(LPCREATESTRUCT lpCreateStruct)
ON_WM_DESTROY(撤销窗口)----void A::OnDestroy()
ON_WM_LBUTTONDOWN(按下鼠标左键)----void A::OnLButtonDown(UINT nFlags,CPoint point)
ON_WM_LBUTTONUP(释放鼠标左键)----void A::OnLButtonUp(UINT nFlags,CPoint point)
ON_WM_MOUSEMOVE(移动鼠标指针)----void A::OnMouseMove(UINT nFlags,CPoint point)
ON_WM_PAINT(窗口需要重新绘制)----void A::OnPaint()
ON_WM_CLOSE(应用程序结束)----void A::OnClose()
ON_WM_SIZE(窗口尺寸被调整)----void A::OnSize(UINT nType,int cx,int cy)