/// <summary>
/// executes the undo or redo to a part or its group
/// </summary>
/// <param name="part"></param>
///
public void PlayState(SceneObjectPart part)
{
part.Undoing = true;
SceneObjectGroup grp = part.ParentGroup;
if (grp != null)
{
grp.doChangeObject(part, data);
}
part.Undoing = false;
}