docs: function(npos, pos, width, height){
        // TODO(nico): be more precise...
        width /= 2; 
        height /= 2;
        var dist = (width + height) / 2, 
            diffx = npos.x - pos.x, 
            diffy = npos.y - pos.y, 
            diff = diffx * diffx + diffy * diffy;
        return diff <= dist * dist;
      }