Both are wonderful options for some use cases. I would also take one of thise approaches for the simple demo in the blog post. But the system UI that is also l

Both are wonderful options for some use cases. I would also take one of thise approaches for the simple demo in the blog post. But the system UI that is also linked in there is something that goes beyond what you can do with e.g. zenity. This kind of puts (almost) all the power of a modern UI description language in reach of shell scripts.