private void appendSaveToolStripMenuItem_Click(object sender, EventArgs e)
{
if (pcc == null)
return;
SaveFileDialog d = new SaveFileDialog();
string extension = Path.GetExtension(pcc.FileName);
d.Filter = $"*{extension}|*{extension}";
if (d.ShowDialog() == DialogResult.OK)
{
pcc.save(d.FileName);
MessageBox.Show("Done");
}
}