public void ShowByControl(Control ctl, Point screenpos)
{
if (ctl == null)
{
throw new ArgumentNullException("ctl");
}
this.Location = screenpos;
//filters
Application.AddMessageFilter(_mousefilter);
Form mainfrm = ctl.FindForm();
if (mainfrm != null)
{
_activationfilter.AssignHandle(mainfrm);
}
base.Show();
}
