Graph 2D Library for Graphical User Interfaces

I'm trying not to think of the abstract class using virtual functions as the one and only means for writing graphical user interfaces. One of the design objectives of elements is that it has to have the clarity of API using modern C++. So you can actually have a compile time representation of the GUI interface without having to call virtual functions necessarily. I still need virtual functions and type erasure in general to store widgets into vectors. But for a large portion of how you're using the library, you're able to capture the essence of the elements composition without having to go to virtual functions.