> I don't think we really see any modern UI library/framework adopting inheritance as a valid pattern at the component level, precisely due to the problems of l

> I don't think we really see any modern UI library/framework adopting inheritance as a valid pattern at the component level, precisely due to the problems of leading developers down the path of creating potentially incorrect abstractions & being too painful to fix when UI can potentially change quite a bit structurally. Composition has the exact same problem in this respect. * Object A * Object B * Object C * Object A * Object B Object C is composed of Object A and Object B. Now go and write code that has instances of Object C. Can you remove Object A without side effects? The amount of pain you experience from removing Object A from Object C isn't related to composition or inheritance. It's related to how often you use a particular object. Furthermore, if you're a library author, pain and inflexibility can arise from how API customers react to breaking changes ( badly ). In this case, it really doesn't matter whether or not you're using inheritance or composition. It amazes me how many programmers cannot seem to understand this.