code: public void centerOnTile (int tx, int ty)
      {
          Rectangle trect = MisoUtil.getTilePolygon(_metrics, tx, ty).getBounds();
          int nx = trect.x + trect.width/2 - _vbounds.width/2;
          int ny = trect.y + trect.height/2 - _vbounds.height/2;
  //         Log.info("Centering on t:" + StringUtil.coordsToString(tx, ty) +
  //                  " b:" + StringUtil.toString(trect) +
  //                  " vb: " + StringUtil.toString(_vbounds) +
  //                  ", n:" + StringUtil.coordsToString(nx, ny) + ".");
          setViewLocation(nx, ny);
      }
docs: Moves the scene such that the specified tile is in the center.