Method setItemGrayed

packages/fairygui/src/widgets/PopupMenu.ts:171–176

* Set item grayed state by name * 通过名称设置菜单项灰色状态

(name: string, bGrayed: boolean)

     * 通过名称设置菜单项灰色状态
     */
    public setItemGrayed(name: string, bGrayed: boolean): void {
        const item = this._list.getChild(name);
        if (item && item instanceof GButton) {
            item.grayed = bGrayed;
        }
    }

    /**
     * Set item checkable state by name