Build your UI in Adobe Animate, export it to JSON and bitmaps with the provided JSFL script, and you forget about lots of positioning magic numbers in your code.
From the readme: "ComponentClip build itself with provided JSON and atlases, and UIComponentPrototype will help to control them, switch states, listen to click, drag and other events.
In addition, UIComponentPrototype and it's children classes don't mind, if they have a real clip instance in current state or at all, so nothing bad happens, for example, if you remove some button instance in your window in Animate document and keep it's UIComponentPrototype instance.
All bitmaps are exported to png files with the same folder structure as in the Animate document library. Pack them to atlases using TexturePacker or other tool you like."