Where to look to begin modifying VR Editor?

I was wondering if anyone could point me to the starting point in the code, where to begin modifying the actual interface of the VR editor itself. Without waving my arms around - it is that space that I would like to modify, but my experience is in scientific computing not anything involving graphical user interface. Does anyone know any resources for this goal? Most of the resources that I have found for C++ programming only deal with simple examples, and none of them discuss how to modify the VR editor itself.

I’m interested in integrating BLUI, so that you could do Google Search or other web type activities without having to leave the editor.