private void editbtn_Click(object sender, EventArgs e)
{
if (E == null)
{
E = new edititem();
E.FormClosed += new FormClosedEventHandler(E_FormClosed);
E.Show();
}
else
{
E.Activate();
}
}
void E_FormClosed(object sender, FormClosedEventArgs e)
{
E = null;
}