It’s the best drag and drop interface builder I’ve seen in an open source project and it’s cross platform and compiled to static binaries for easy distribution.
In BASIC land, the QB64pe project has a maintainer for Inform-pe, a pretty straightforward drag & drop interface builder:
https://qb64phoenix.com/forum/showthread.php?tid=1311
Here's an example running under QB64 (though not Phoenix Edition/pe):
https://www.youtube.com/watch?v=a9pNGBaIr94
Background on the Phoenix Edition:
https://qb64phoenix.com/forum/showthread.php?tid=259
There's also Purebasic and Gambas, though Gambas isn't cross-platform...
https://gambas.sourceforge.net/en/main.html
Zooming further out you have e.g. Defold and Cerberus X, which I'm not sure about the drag & drop but GUIs are certainly doable.
https://www.cerberus-x.com/community/index.php?pages/about/
Then there are Wonkey and wxBasic...
https://wonkey-coders.github.io/
Et cetera... :-)
Personally I'm pretty fascinated by the way these projects typically center around a traditional forum, with various software structures in place that shape the user experience.
For example, prolific library authors may be invited to publish directly to their own subforum and kind of use it as their own website, etc.
When new projects start, spin off, fork, etc, the forum is often the first part of the user experience to see created, frameworked and decorated in depth.
One advantage of this particular coding ecosystem is that you can use Delphi docs, techniques and tutorials as well, which can be helpful to know.
But if your specification is "cover all aspects of Lazarus itself at confirmed 1:1 functionality with the current major version" then it might be a difficult ask.
There are some really great resources out there, but they are not going to meet every definition of decent docs.
For me it was enough to watch some YouTube tutorials[1] to get the gist, identify some idiomatic workflows, start building, do a bit of searching in different documentation resources, and ask follow-up questions at the forum.
It's nice that we can also ask ChatGPT for help these days too.
1. I thought this was a good example of a set of YouTube tutorials demonstrating working with Lazarus: https://youtube.com/playlist?list=PLYT8oqHJjWzTsIzzGN-Y1wKM9...
The drawback is that there is usually relatively little information outside of the forum and uncommon that code is shared on things like github, instead code sharing is typically done by copy&paste on the forum, which makes it a bit harder to track and standardize conventions.
I wrote the linked article because I wanted to explore dead easy programming environments for people who liked BASIC and VB, partly because 40 years ago, I liked BASIC myself.
C++ is the anti-BASIC. So are virtually all modern programming tools. Vast complex hard languages designed by professionals for professionals. Anything with braces in it wasn't designed for beginners.
Python is also very much a C-ish Unix-ish tool, too. It's just that Unix folks are so used to this that they don't notice.
What does % mean? Oh, well, it depends. Where?
How do you print a number? Oh, well, it depends. You can use %d but also %f but only if you want so many decimal places...
This is ugly crufty stuff, but if you're used to that and grew up with it, it's normal.
Python only looks easy and simple if you're used to C.