/// <summary>
/// method : mnuOpen_Click
/// </summary>
/// <param name="sender">The sender.</param>
/// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
private void mnuOpen_Click(object sender, EventArgs e)
{
CheckForChanges();
if (dlgOpen.ShowDialog() == DialogResult.OK)
{
calculation.LoadFromFile(dlgOpen.FileName);
}
dlgSave.FileName = dlgOpen.FileName;
changed = false;
}