private void downBtn_Click(object sender, EventArgs e)
{
int index = listBox1.SelectedIndex;
if (index == listBox1.Items.Count - 1 || listBox1.SelectedItem == null)
return;
string dir = listBox1.SelectedItem.ToString();
listBox1.Items.RemoveAt(index);
listBox1.Items.Insert(index + 1, dir);
listBox1.SelectedIndex = index + 1;
modified = true;
ok.Enabled = apply.Enabled = modified;
}