Please don't store any instance of objects in a property in the default class you are exporting (line 24 `prefs.js`) that won't allow the garbage collector to do its job after window close: [EGO Review Guidelines: Destroy](https://gjs.guide/extensions/review-guidelines/review-guidelines.html#destroy-all-objects) If you don't want to make it local to `fillPreferencesWindow()` function, you can clean up on: ```js window.connect('close-request', () => { // clean up here }); ```