Hello GTK devs in particular, but also GTK users in general.
First - I wrote this in my GTK-based editor. I can’t stand the online
editor discourse uses. Perhaps this works on smartphones, but on my
oldschool desktop system, using a “classical” GTK based editor is
sooooo much more efficient for me, time-spent-wise. Anyway - I
mention this because I end lines usually at around ~80 chars or so,
so you may see some line breaks in discourse (perhaps). It all
looks great if you were to look at my monitor though … 
This here is mostly a “plea”, a request. It’s along the lines of
“please don’t forget us hobbyist hackers!”.
I will explain this soon, and provide the context.
I am a ruby-guy, that is, I have been writing ruby code since
almost 20 years by now. Even though I am not as active anymore,
I still write ruby code almost daily. Mostly, I just maintain
my projects these days though.
Anyway.
Part of the code I wrote is in ruby-gtk. That is, I work with
the “inofficial” bindings here. These work quite well, but for
various reasons I am stuck with gtk2. (ruby-gtk3 unfortunately
does not offer the same functionality, and “monkey patching”
is also not easily possible due to the weird way how gobject
introspection appears to work, but this is NOT the main point
I want to make for this here).
I think I started to write ruby-gtk code since 2005 or so.
During that time, I noticed numerous projects, but also ruby
users, vanish and disappear. Now: this does not have much
to do with GTK itself, and this happens in most languages,
even python. But still it is sort of sad when you notice
that there is a decline in how many people write code.
A decline is not good for any programming language or project.
But this note is not about a decline, either.
For those of us who STILL write, and maintain code, e. g.
ruby-gtk, they would often like to CONTINUE doing so.
And the note here is ultimately about that part.
Again, for many reasons, transitioning into ruby-gtk3 would
bring specific disadvantages for me. I may still do so in
the long term, but I have to invest a lot of time, with the
end result of reduced functionality in my applications (which
I don’t want to do, for obvious reasons … think you invest
20 hours, and then you have fewer features than before.
Time well spent? Hmmmmmm.)
This is where I hope that GTK4 will actually really improve
the situation overall. At the least I project hope - perhaps
this is just wishful thinking. 
The thing is, to me … the better GTK4 will be, the more
successful it can be, the better for the WHOLE gtk ecosystem,
including downstream bindings (e. g. ruby code).
One thing that I have found over the years to be EXTREMELY
important is … documentation. The docs for gtk are not
great, IMO, but they are not terrible either. Still,
documentation is really important. It allows downstream
developers to make their own code work better, and their
own implementation be better too (since they can read the
official docs).
So, what is this note about, then?
Well. I am following the GTK4 development blog here.
GTK4 seems to look to really improve on many things GTK3
did not get right; and perhaps GTK4 will finally be
better than GTK2, or at the least be as good as GTK2
was (again, from my point of view, in regards to the
ruby-gtk bindings, the gtk2 bindings are better than
the gtk3 bindings).
So my plea is really quite trivial: please don’t forget
us! The better GTK4 will be, the more polished it is,
the better the documentation, the better the whole
ecosystem will end up as well.
As I am right now, with the importance of the www in
general, I wonder whether it is still worth my time
to write any ruby-gtk specific stuff. I still do it
because ruby itself is awesome, and I have a lot of
ad-hoc code and extensions for ruby-gtk2 too, so that
part is fun. But I feel like deadlocked into the past
since transitioning to ruby-gtk3 already would bring
in disadvantages. So to me this is a question of how
good gtk4 will be. And if it is “not good enough” then
I think I’ll have to follow the trail of literally
everyone else, and enter the abysmal world of
javascript - simply because I am less restricted with
the www-stack than with “oldschool” GUIs. (That is
also valid for qt, by the way; just that the ruby-qt
bindings died past qt3, also in parts because qt
got sooooooooo big that no hobbyist is going to
maintain that really. Even ruby-qt4 is incomplete,
and qt6 is going to be released probably next year?)
I am not sure if this note has a point or not, but if
one or two upstream GTK dev reads it, and at the least
considers this too, this may help.
PS: I am aware of gobject-introspection being praised
as the perfect solution for everything, but in regards
to the ruby-gtk bindings, the old handwritten bindings
are so much better than the gobject-variants. I simply
don’t have the same feature parity; my monkey-patched
“module Gtk” works fine on ruby-gtk2 but does not work
AT ALL on ruby-gtk3. I could expand on this but the
more important thing is that the “gobject-all-the-things”
does not automatically mean everything REALLY has gotten
better. And in that particular context, it actually would
make a whole more sense to just be done with it, use
javascript and Google’s adChromium monopoly, even
electron, no matter how much RAM and babies it eats …
all of which is the “logical path” to pursue. But before
that, I really want to be hopeful and think of GTK4
being a REALLY great GTK, even better than gtk2. So
please don’t forget on awesome upstream documentation
AND downstream hobbyists coders. (In regards to
documentation: I also include examples. I learn best
with examples of working code.)