Check out a guide to scripted extensions in the newest version by Luciano Iurino.
Scripted Extensions via Blueprint scripting need to be done via Blutility. If you don’t know what it is, Blutility is just a special type of Blueprint that helps create custom Editor-callable functions and events.
In order to use Blutility, you need to enable it in the Editor Preferences:
[Optional] Some of the tools exposed for the Editor scripting will only appear if you enable the Editor Scripting Utilities in the Plugin section:
First we need to create a new Blutility asset:
When asked for the parent class, just select ActorActionUtility if you want to extend the Editor to handle Actors in the scene:
Once created, if you want to open it for editing, don’t just double-click on it: it would just open an empty window. Instead, right-click on it in the Content Browser and click on Edit Blueprint: