public void ChangePos(long pos, object sender, bool refreshSender = false)
 {
     if (_state.Pos == pos)
     {
         return;
     }
     _state.Pos = pos;
     if (mainView != sender || refreshSender)
     {
         mainView.Refresh();
     }
     if (scr != sender || refreshSender)
     {
         scr.Refresh();
     }
     //start loading?
     LoadLazyLogIfNeeded();
     //no need to serialize, non-persistant property changed
 }