Method isItemChecked

packages/fairygui/src/widgets/PopupMenu.ts:216–225

* Check if item is checked by name * 通过名称检查菜单项是否选中

(name: string)

     * 通过名称检查菜单项是否选中
     */
    public isItemChecked(name: string): boolean {
        const item = this._list.getChild(name);
        if (item && item instanceof GButton) {
            const c = item.getController('checked');
            if (c) {
                return c.selectedIndex === 2;
            }
        }
        return false;
    }

    /**
     * Remove item by name