Method setPosY

packages/fairygui/src/scroll/ScrollPane.ts:317–323

* Set vertical position with animation * 设置垂直位置（带动画）

(value: number, bAnimate: boolean)

     * 设置垂直位置（带动画）
     */
    public setPosY(value: number, bAnimate: boolean): void {
        value = clamp(value, 0, this._overlapHeight);
        if (value !== this._scrollY) {
            this._scrollY = value;
            this.posChanged(bAnimate);
        }
    }

    /**
     * Scroll to top