Geany is a small and lightweight Integrated Development Environment. It was developed to provide a small and fast IDE, which has only a few dependencies from other packages. Another goal was to be as independent as possible from a special Desktop Environment like KDE or GNOME - Geany only requires the GTK3 runtime libraries.
I want to like geany. However, its just not customizable and it lacks support for a lot of things.
I would say it is customizable, but I think it is relatively difficult to customize compared to a lot of other editors (e.g. Emacs). I think Geany is a nice, free/libre alternative to VSCode, and about as difficult to customize as VSCode, but does not have quite as many extensions available for it due to the fact that unlike VSCode, Geany is not supported by a multi-billion dollar company with the goal of embracing, extending, and extinguishing all other competing editors.
Geany Extensions are written in C which is not a scripting language and so unlike in Emacs you can't just write a quick 2 or 3 line script like you would in Emacs to solve some unique text-editing problem.
Geany does have extensions for Python and Lua scripting, but there is almost no ecosystem of Lua or Python scripts, and trying to access the editor features from Lua or Python requires deep knowledge of the Geany Gtk3 API. Compare this to something like the "Lite" text editor which has the whole user interface written in Lua, and therefore you can write fairly elaborate text editing scripts and user interfaces entirely in Lua. You just cannot do this with Geany.
In what world is Vscode not customizable? I guess the overall UI structure is fairly static but you can move bits left to right, hide and show stuff, colour themes, set your own shortcuts etc
themes, plugins, ridiculously easy custom configurations/build commands etc
you can even control the window manager from config files if you want to, its insanely customisable
lacks support for alot of things
edit: trying to sound less snarky, but do you have alot of examples?
i could see these criticisms arising from a quick glance. or we may have slightly different definitions of these terms. which is fair enough.
imo geany's ratio of features to weight is remarkable, perhaps singularly so?
I just know I wasn't able to get code suggestions, highlighting or error highlighting working. There might be a way but I spend a bunch of time on it and accomplished nothing. If there is a way it isn't obvious
I use geany for coding in LaTeX, and occasionally teaching myself some programming stuff when I have free time. I'm aware it's not a great choice for experienced programmers, but I don't really need something feature-rich and extensive, so I appreciate the simplicity.