Development Experience concerns

Hi guys!

I found this project very interesting in the long term, however and may be I'm wrong, but it seems that it's hard to on board to contribute into this projects since it's not clear what is an input and output of each UI component. For example both themes have it's own component realization that's why you need tests for each of them. Also it's hard to switch from one theme to another depending on the clients OS.

Just an idea why not to extract the components codebase itself having all possible props declared and handled in place and separate macOS and Windows styles as themes. I saw issue talking about styled-components, that's a great idea, but it will be hard to rewrite everything in a moment because of all conditions.

And I see that Functional Components & Recompose are a good tools to refactor codebase to. When the props declaration will be in place it'd be easy to generate consistent docs. And having styles splitted from the implementation it'd be easy to add other themes like for Ubuntu/Windows Classic/etc.