private Point LocationOnScreen(Control c)
{
Console.WriteLine(c.PointToScreen(new Point(0,0)).ToString());//相对于0,0 位置的,带标题栏
Point retval = new Point();
do
{
retval.Offset(c.Location);
c = c.Parent;
}
while (c != null);
Console.WriteLine(retval.ToString());//不带标题栏
return retval;
}