public CIMPolygonSymbol GetDefaultPolygonSymbol()

{
  //Note: Must be on QueuedTask.Run
  //Get the default font (see also 'SymbolFactory.Instance.DefaultFont')
  var def_font = ApplicationOptions.TextAndGraphicsElementsOptions.GetDefaultFont();
  System.Diagnostics.Debug.WriteLine(
    $"\r\ndefault font: {def_font.fontName}, {def_font.styleName}");

  //Get the default graphics element symbols - point, line, poly, text
  var ptSymbol = ApplicationOptions.TextAndGraphicsElementsOptions.GetDefaultPointSymbol();
  var lineSymbol = ApplicationOptions.TextAndGraphicsElementsOptions.GetDefaultLineSymbol();
  var polySymbol = ApplicationOptions.TextAndGraphicsElementsOptions.GetDefaultPolygonSymbol();
  var textSymbol = ApplicationOptions.TextAndGraphicsElementsOptions.GetDefaultTextSymbol();
}