How to add a dockable window inside the level editor?

I am getting my feet wet with plugin programming… What is the correct way to add a window that docks inside the level editor? I know about the usage of

FGlobalTabmanager::Get()->RegisterTabSpawner()

but that adds a global window. As I understand it,

levelEditor.GetLevelEditorTabManager()

will be unavailable (null) inside StartupModule(), so that isn’t an option either.

I have seen some people use the FLevelEditorModule::OnTabManagerChanged() event, but I don’t know how I receive that event in my module - it’s not in IModuleInterface, can I register for it?

Just a thought, but maybe you can extend FLevelEditorModule instead of IModuleInterface if you want access to OnTabManagerChanged.