Create Directory Rollout Window

I’m trying to create an easy way to select large amounts of files. Unity gives you this interface when you import a package, but I can’t find anything about creating a foldout window like this. Is there an easy to do this? Right now it looks like I have to use EditorGUI.Foldout, along with toggles, but I’d rather make sure I’m not missing anything before I implement it from scratch.

38515-importui.png

I know this is 5 years late, but check out Unity - Manual: TreeView