Hello,     

Implementing such an API reference documentation sounds quite promising and very useful. We will consider it in the future improvement of the documentation. However, I would like to note that the current API reference offers a search box on the top left side of the page. Thus, you can navigate to the desired control easily, e.g. RadButton. After opening the found result, you can investigate the whole structure of inheritance and have a look at the properties, methods and events at the specific level: https://docs.telerik.com/devtools/winforms/api/telerik.wincontrols.ui.radbutton.html

I hope this information helps. If you need any further assistance please don't hesitate to contact me. 

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik