public void checkCollision(NicoLabel label, double scale, Panel container)
 {
     foreach(NicoLabel item in labels)
     {
         if (label == item)
         {
             continue;
         }
         if (label.collideWith(item))
         {
             if (label.moveDown(container.ActualHeight))
             {
                 // moved done
                 checkCollision(label, scale, container);
                 return;
             }
             else
             {
                 // overflow
                 return;
             }
         }
     }
 }