in public/bubblesets.js [105:111]
this.intersects = function(rect) {
if(that.width() <= 0 || that.height() <= 0 || rect.width() <= 0 || rect.height() <= 0) return false;
return (rect.maxX() > that.minX() &&
rect.maxY() > that.minY() &&
rect.minX() < that.maxX() &&
rect.minY() < that.maxY());
};