/// <summary>
/// Saves the external source's settings to a file
///
/// AWGControl:SSave
/// </summary>
/// <param name="extSource">the EXTSOURCE object</param>
/// <param name="filename">filename to save settings to</param>
/// <param name="msus">mass storage unit specifier aka drive</param>
public void SaveExtSrcSettings(IEXTSOURCE extSource, string filename, string msus)
{
if (msus != "")
{
msus = "," + "\"" + msus + "\"";
}
extSource.SaveExtSrcSettings(filename, msus);
}