@jterrain said in how to make tab bar appear vertically in notepad ++:

but implementation of actual vertical tabs would work better.

We have a Feature Request FAQ:
https://community.notepad-plus-plus.org/topic/15741/faq-feature-request-or-bug-report

@Maxitrol-Mat said in 4k resolution:

While some things look good, some other things look microscopic.

One thing that may help: In Preferences > Toolbar, try choosing a “large” UI option.