Bloc has improved a lot in the past year. It is ready for your
experiments. Here is one of mine:

https://github.com/StephanEggermont/Presentations

Bloc supports the creation of beautiful GUIs,
with nice interactions. This one shows a number
of different ways of using drag-and-drop.

https://github.com/StephanEggermont/Presentations

A video demonstrating it is at:

https://vimeo.com/290163891