private void btn_allPlan_Click(object sender, EventArgs e)
{
this.panel.Controls.Clear();
AllTrainPlan p = new AllTrainPlan();
p.TopLevel = false;
p.Dock = DockStyle.Fill;
this.panel.Controls.Add(p);
p.Show();
}
private void btn_trainPlan_Click(object sender, EventArgs e)
{
LeftMenu(sender);
this.pan_change.Controls.Clear();
AllTrainPlan p = new AllTrainPlan();
p.TopLevel = false;
p.Dock = DockStyle.Fill;
this.pan_change.Controls.Add(p);
p.Show();
}