Is it possible to make an editor GUI?

Hi all,
Simple question, Is it possible to make an editor GUI. What are the classes that I can use for this?
Because I have a hard time of finding good information on the website.

Your question is extremely vague, what kind of GUI do you want exactly? seems relevant to your query

Thnx that is close for what what I’m looking for.
Sorry for being vague I come from Unity background and in unity it’s like 3 lines for creating a custom editor UI window.

Use Slate, its same ui system that ue4 editor uses, search slate in docs or wiki