add a few things:

* test case with folders/subfolders
* renaming items by double-clicking them
* naive drag test

TestArea.tscn

@@ -5,23 +5,60 @@
 [sub_resource type="GDScript" id=1]
 script/source = "extends Control
 
+onready var control_tree: ControlTree = $ControlTree
+
 var i
 var j
 
+var files: Array = [] # Array[FileDef]
+
 func _ready() -> void:
-	pass
+	files = get_dir_contents(ProjectSettings.globalize_path(\"res://test_dir\"))
+	construct_tree(files)
 
 
-func _on_Button_pressed() -> void:
-	i = $ControlTree.add_item('test')
+func get_dir_contents(path: String) -> Array:
+	var res = []
+	var dir = Directory.new()
+	if dir.open(path) == OK:
+		dir.list_dir_begin(true)
+		var fname = dir.get_next()
+		while fname != \"\":
+			var f = FileDef.new()
+			f.path = fname
+#			print(f.path)
+			if dir.current_is_dir():
+				var a = get_dir_contents(path.plus_file(fname))
+				f.contains.append_array(a)
+
+			res.append(f)
+			fname = dir.get_next()
+		dir.list_dir_end()
+	return res
 
 
-func _on_Button2_pressed() -> void:
-	j = $ControlTree.add_item('test2', i)
+func construct_tree(from: Array, parent: ControlTreeItem = null):
+	for f in from:
+		var item = control_tree.add_item(f.path, parent)
+		if f.contains:
+			item.editable = false
+			construct_tree(f.contains, item)
 
 
-func _on_Button3_pressed() -> void:
-	$ControlTree.add_item('test3', j)
+#func _on_Button_pressed() -> void:
+#	i = $ControlTree.add_item('test')
+#
+#
+#func _on_Button2_pressed() -> void:
+#	j = $ControlTree.add_item('test2', i)
+#
+#
+#func _on_Button3_pressed() -> void:
+#	$ControlTree.add_item('test3', j)
+
+class FileDef:
+	var path: String
+	var contains: Array # Array[FileDef]
 "
 
 [node name="TestArea" type="Control"]