It's a simple tree view based on an official example on the website of Vue.js, expanded a little bit just for learning Vue.
- Single click on folder name to toggle folder.
- Double click on item name to make folder.
- Single click on "[ e ]" by the right of item of folder name to edit the name. When in the editing mode, press "enter" or click elsewhere (blur) to switch back to text display.
- Single click on "[ x ]" by the right of item of folder name to delete.
- Single click on "[ + ]" at the bottom of item children list to append new child item.