I've been following this app for a while. Worth noting that the author is also a very talented graphic artist and demoscener. Works created with this tool frequently appear in various demoscene compos.
Nice! The code looks pretty neat! And also somehow clean. I like those projects, without all those boring constraints you have in "enterprise" or even worse start-up code.
Nice. Vanilla js with a pretty clean code. From a quick look there is some components architecture and they are decoupled via an events bus. I used to implement evented architectures in winform apps in the past. On the one hand it may seem insane but in practice it was a really good choice.