C# - How to make Notepad++ in WPF (WPF notepad 'tutorial')

(GitHub link at the bottom of the description) (also, not sure what happened to the quality, most likely just the compression. 1080p videos take FOREVER to render, so i had to go with 720p)
Making notepad in WPF or Winform is fairly simple: you make a massive textbox, some menuitems with the common commands like open, save, formatting, etc, just like Windows' notepad.
However, notepad++ has some unique features like being able to open 100s of files at once, and this video shows how to do that (part 2 coming soon).

The code mainly consists of using a 'parent' control (the TabControl) and adding 'children' to it (the TabItems). And inside those tabitems you add the textbox (as well as a context menu for the textbox). The program uses Lists to list the tabitems, data and paths of the files. It also has a 'selected item' integer which is used for basically matching the selected TabItem to pull the textbox control and thus it's text to then be able to save it.

Github Link:
i accidentally deleted the one for this video.. rip
anyway, here's the link to the version ive been making for the past like year (not constantly... just every now and then)
https://github.com/AngryCarrot789/sharppad

Also: Music.
1st Song: Maf - Mafland (2012 Remake),
2nd Song: Aduro - JensKiilstofte,
3rd Song: Andrew Applepie - Keep On Trying.