/// <summary>
/// Opens a new change group used to batch several changes.
/// ChangeGroups work as transactions and are used to support the Undo/Redo system.
/// </summary>
public override ChangeGroup OpenGroup(string changeGroupTitle, ICollection <DesignItem> affectedItems)
{
if (affectedItems == null)
{
throw new ArgumentNullException("affectedItems");
}
UndoService undoService = this.Services.GetRequiredService <UndoService>();
UndoTransaction g = undoService.StartTransaction(affectedItems);
g.Title = changeGroupTitle;
return(g);
}
