/// <summary>
/// Deshace la última acción.
/// </summary>
public void Undo()
{
if (undoPtr != null)
{
model.Modified = true;
undoing = true;
Rollback();
currentAction = undoPtr.Value;
currentAction.Undo();
undoPtr = undoPtr.Previous;
currentAction = new ActionList();
undoing = false;
}
}