wondering when to support pull-to-refresh?

[liangdong]

the refresh() method always reset Y to 0 when bouncing, and this really confused me!

    resetPosition: function (time) {
        var x = this.x,
            y = this.y;

        time = time || 0;

        if ( !this.hasHorizontalScroll || this.x > 0 ) {
            x = 0;
        } else if ( this.x < this.maxScrollX ) {
            x = this.maxScrollX;
        }

        if ( !this.hasVerticalScroll || this.y > 0 ) {
            y = 0;
        } else if ( this.y < this.maxScrollY ) {
            y = this.maxScrollY;
        }

        if ( x == this.x && y == this.y ) {
            return false;
        }

        this.scrollTo(x, y, time, this.options.bounceEasing);

        return true;
    },

Thanks!