After trying KDevelop, Kate, Eric, Sypder etc. I thought I could write my own.
I had a simple plugin system in mind, with similar to LSP style features (VSCode was not released that time).
The UI was inspired by Blender. Blender has such a fluent UI where you can customize everything.
So I wrote a small GTK library to mimic Blender's UI.
And started development of the text editor. But then got busy with school and left the idea.
Then I found out Emacs and Doom Emacs and dropped the idea of a custom text editor eventually :).
Two reasons: 1. Emacs was 200% configurable, which is what I wanted to implement in my editor too.
2. Emacs worked pretty good on my 2 GB laptop with all the goodies.
But compared to 10 years back (when I was trying these things), it is quite easy now thanks to LSP, Tree-Sitter etc. But it is always a fun ride with algorithms and data structures. :)
I haven't used VSCode, but it is really nice how it changed the text-editor platform with LSP etc.
Now I have a laptop with 24 GB RAM but I'm forever vendor locked-in with Emacs :D