You should take a look on Qt and QML The render tree is only one aspect whis is dealt by JS frameworks, because all of them are sitting on the fat neck of brows

You should take a look on Qt and QML The render tree is only one aspect whis is dealt by JS frameworks, because all of them are sitting on the fat neck of browser. For a stand-alone UI you will need not only bubbling through layers events like mouse clicks but also non-layered functionality like keyboard focus, tab orders and screen reader support for blind users.