change background color of gnome shell main panel based on label of input method

hack.js

(async () => {
    const Main = await import('resource:///org/gnome/shell/ui/main.js');
    const { default: GLib } = await import('gi://GLib');

    const ind = Main.panel.statusArea.keyboard;
    const mgr = ind?._inputSourceManager;
    if (!mgr) return;

    const update = () => {
        const text = ind._indicatorLabels[mgr.currentSource?.index]?.get_text();
        if (text != null) {
            Main.panel.set_style(['A', 'en', 'us', 'EN'].includes(text)
                ? 'background-color: transparent;'
                : 'background-color: royalblue; transition: background-color 0.2s;');
        }
    };

    if (ind._rimeSig) mgr.disconnect(ind._rimeSig);

    ind._rimeSig = mgr.connect('current-source-changed', () => {
        GLib.idle_add(GLib.PRIORITY_DEFAULT_IDLE, () => (update(), GLib.SOURCE_REMOVE));
    });

    globalThis._rimeMonitorStop = () => {
        if (ind._rimeSig) mgr.disconnect(ind._rimeSig);
        ind._rimeSig = null;
        Main.panel.set_style('background-color: transparent;');
        delete globalThis._rimeMonitorStop;
    };

    update();
})();