Truly native and cross-platform GUI with declarative DSL for its specification, built-in reactive framework (no FRP though), and semantically rich evaluation model (e.g. note that calculation of typed expression is a one-liner).
By the way, the library used in that blog post is also truly native and cross-platform. Keera has apps and games that work on Windows/Mac/Linux/Web/iOS/Android, all from the same code.
Most of the Red GUI examples I know of are "programming in the small", like CRUD interfaces, games, and various interactive environments. [1, 2]
The graphical engine relies on OS widgets internally right now, which are resource-heavy and don't scale well (at least on Win32 backend each widget is just that, a window); in the future, more lightweight graphical objects (aka GOBs) will be introduced for use-cases like spreadsheets and data-intensive apps, there's already a PoC for that. [3]
For evaluation and benchmarking, I recommend to check out 7GUIs project [4] and add Keera Hails entries to it; here [5] is Red implementation, for comparison. Some tasks in it directly address MVC separation of concerns.
[1]: https://github.com/red/code
[2]: https://github.com/red/red/wiki/%5BLINKS%5D-Projects-showcas...
[3]: https://github.com/qtxie/red/tree/GOB
