void tnt_FormClosed(object sender, FormClosedEventArgs e)
{
tnt = null;
}
private void takeNewTrainingToolStripMenuItem_Click(object sender, EventArgs e)
{
if (tnt == null)
{
tnt = new TakeNewTraining(n);
tnt.MdiParent = this;
tnt.FormClosed += tnt_FormClosed;
tnt.Show();
}
else
{
tnt.Activate();
}
}