protected override void DiscardUndoUnit(UndoEngine.UndoUnit unit)
{
base.DiscardUndoUnit(unit);
if (_undoUnits.Count > 0 && Object.ReferenceEquals(unit, _undoUnits.Peek()))
{
_undoUnits.Pop();
}
}
protected override void AddUndoUnit(UndoEngine.UndoUnit unit)
{
_undoUnits.Push(unit);
_redoUnits.Clear();
}