private static void Invert(IVisio.Window window)
{
if (window == null)
{
throw new System.ArgumentNullException(nameof(window));
}
if (window.Page == null)
{
throw new System.ArgumentException("Window has null page", nameof(window));
}
var page = (IVisio.Page) window.Page;
var shapes = page.Shapes;
var all_shapes = shapes.AsEnumerable();
var selection = window.Selection;
var selected_set = new HashSet<IVisio.Shape>(selection.AsEnumerable());
var shapes_to_select = all_shapes.Where(shape => !selected_set.Contains(shape)).ToList();
window.DeselectAll();
window.Select(shapes_to_select, IVisio.VisSelectArgs.visSelect);
}