It's really good for scrappy prototypes, e.g. here's a water simulation demo I was using to learn Rust [1]. See the "view" menu for more windows.

The code for that is all contained in a single file [2], and IMO it's pretty small for what it does. It was really easy to add/change things while developing, a new button is just a single new line.

[1] https://andreivasiliu.github.io/cybersub/

[2] https://github.com/andreivasiliu/cybersub/blob/master/src/ui...