Method hidePopup

packages/fairygui/src/core/GRoot.ts:142–156

* Hide popup * 隐藏弹出窗口

(popup?: GObject)

     * 隐藏弹出窗口
     */
    public hidePopup(popup?: GObject): void {
        if (popup) {
            const index = this._popupStack.indexOf(popup);
            if (index !== -1) {
                this._popupStack.splice(index, 1);
                this.closePopup(popup);
            }
        } else {
            // Hide all popups
            for (const p of this._popupStack) {
                this.closePopup(p);
            }
            this._popupStack.length = 0;
        }
    }

    private closePopup(popup: GObject): void {
        popup.visible = false;