Method showModalWait

packages/fairygui/src/core/GRoot.ts:195–200

* Show modal wait * 显示模态等待

(msg?: string)

     * 显示模态等待
     */
    public showModalWait(msg?: string): void {
        if (this._modalWaitPane) {
            this.addChild(this._modalWaitPane);
            this._modalWaitPane.visible = true;
        }
    }

    /**
     * Close modal wait