private void btnBack_Click(object sender, EventArgs e)
{
ReplacingLevelForm replacing = new ReplacingLevelForm();
this.Hide();
replacing.ShowDialog();
this.Close();
}
//go to replacing form
private void btnReplacing_Click(object sender, EventArgs e)
{
ReplacingLevelForm l1 = new ReplacingLevelForm();
this.Hide();
l1.ShowDialog();
this.Close();
}