To be honest though, I think the biggest missed opportunity in racket is the single dispatch object system, used particularly by racket/gui. For some reason the core racket folks weren't smitten with CLOS and didn't go the Guile route of implementing something similar to it (Guile has GOOPS, which is related to Tiny-CLOS.)
A runtime multiple dispatch stub is available as a lib, though (https://docs.racket-lang.org/multimethod/index.html)
The Racket class system has seemed fine to me for the GUI tookit (except for me not liking typing `send`). But if you find a limitation for that purpose, please post about it on the `racket-users` email list. The core developers are there. https://groups.google.com/forum/#!forum/racket-users/
FWIW, Racket (when it was still PLT Scheme) got a tiny-CLOS-alike around the time that Guile got GOOPS: Eli Barzilay made Swindle: https://docs.racket-lang.org/swindle/
CLOS is neat, and I'd be interested to see someone make a CLOS (maybe including a MOP?) for Racket, atop the modern Racket `struct` and other features. (If you tune it, try tuning for the tentatively forthcoming Chez backend to Racket, rather than for the current JIT. IIRC, Swindle was written before the JIT.)
No offense to the design team intended, I'm sure they had different priorities for which single dispatch made sense.
When you encounter yet another one, learning it is usually a matter of seeing which set of semantics it provides (probably all of which you've seen before), and the exact way they do it.
Though one nice feature they included with Racket's `class` library, which was unusual (but not new) at the time, is mixins: https://docs.racket-lang.org/guide/classes.html#%28part._.Mi...
I've used Tkinter with python to make a whole bunch of quick utilities (sync tools for non-techies, XML editing stuff for file applications which lack needed tools, etc.) and think it's very under appreciated.
Also the difference between 60MB and 100MB isn't huge, so using the word ridiculous is IMO a bit over-dramatic.
> PyQt is one of the most popular Python bindings for the Qt cross-platform C++ framework.
And why are you comparing an editor to a GUI framework? Or is there a GUI framework also called Sublime?