void CMyDlg::OnRButtonDown(UINT nFlags, CPoint point)
{
CMenu myMenu;
myMenu.CreatePopupMenu();
myMenu.AppendMenu(MF_STRING, ID_ENTER, "按 Enter 键发送消息");
myMenu.AppendMenu(MF_STRING, ID_CTRLENTER, "按 Ctrl+Enter 键发送消息");
myMenu.TrackPopupMenu(TPM_LEFTALIGN, point.x, point.y, this);
}