ATShellTreeview is Lazarus component, descendant of TreeView, which provides treeview somewhat similar to VS Code editor. It gives "Folder" property which loads the folder to the root of treeview. Only first level of folder is read initially. All sub-folders are read on demand, on unfolding tree nodes. It gives event OnShellItemClick which allows to detect click and double-click on nodes (giving full file path).
It uses helper object ATShellIcons which holds cache of file-type icons. Set of about 290 file-type icons is included in the GitHub repo, it's taken from VS Code project (free license). ATShellIcons detects icons for lot of common file types, and has event OnDetect for additional detection.
ATShellOptions global record holds options of that treeview.
License: MPL 2.0 or LGPL.
Component is not placed on the Lazarus component palette, it must be created at runtime. Use class TATShellTreeview from unit "atshelltreeview", and use unit "atshellbase" too.
Demo project shows how to load icon-set, how to change UI options of treeview. Demo project needs ATFlatControls package.
Screenshot of Explorer test project (it has ATShellTreeview + ATListbox for the tabs list):