Codereview: Beginner text editor

Beginner text editor
I hope you found a solution that worked for you :)
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Thanks to all those great people for their contributions!

(codereview.stackexchange.com/users/67037/m-cekiera)m.cekiera
(codereview.stackexchange.com/users/49695/tim)tim
A special thanks goes out to the (codereview.stackexchange.com/questions/84887/beginner-text-editor)Stackexchange community

I wish you all a wonderful day! Stay safe :)
If anything is off, please write me at peter D.O.T schneider A.T ois42.de

java beginner text-editor swing