private void manageToolStripMenuItem_Click(object sender, EventArgs e)
{
if (am == null)
{
am = new aboutManage();
am.MdiParent = this;
am.FormClosed += am_FormClosed;
am.Show();
}
else
{
am.Activate();
}
}
void am_FormClosed(object sender, FormClosedEventArgs e)
{
am = null;
//throw new NotImplementedException();
}
