You can look at the underlying code on the RIO. When I began to learn all I had were the VB samples in Help and Doug Henig. Now we have auto complete that exposes the object tree - AND YOU CAN BUILD TREEVIEWS ON A FORM RIGHT FROM COMMAND WINDOW.
It's a lot easier now - but still requires some intimate practice time.
Heres a command window treeview:

* Demo Treeview (from scratch) through VFP Command Window
* CREATE the form
ofoo=CREATEOBJECT('form')
ofoo.show
* Add the Image List
ofoo.addobject('ocxImageList','Olecontrol','MSComctlLib.ImageListCtrl.2')
oIL=ofoo.ocxImageList
oIL.imageheight=16
oIL.imagewidth=16
oIL.ListImages.Add(1,"CLOSED",LOADPICTURE("CLOSED.ICO"))
oIL.ListImages.Add(1,"OPENED",LOADPICTURE("OPENED.ICO"))
oIL.ListImages.Add(1,"ON",LOADPICTURE("ON.ICO"))
oIL.ListImages.Add(1,"OFF",LOADPICTURE("OFF.ICO"))
* Add the tree view
ofoo.addobject('ocxTreeView','Olecontrol','MSComctlLib.TreeCtrl.2')
oTV=ofoo.ocxTreeview
oTV.Visible=.t.
oTV.Height=ofoo.Height
oTV.Width=ofoo.Width
oTV.Style= 7  && tvwTreelinesPlusMinusPictureText
oTV.Fullrowselect=.t.
* Assign the imagelist as the treeview's imagelist 
oTV.ImageList=oIL
* These are some sample DBFs I used - dept.dbf supplied parent nodes
SELECT dept
GO top
oTV.Nodes.Add(,1,dept.dept_key,dept.dept_name,"CLOSED","OPENED")
SKIP
* .... empl.dbf supplied the children for the paren nodes.
SELECT empl
GO top
oTV.Nodes.Add(empl.dept_key,4,empl.dept_key+empl.empl_key,empl.empl_name,"OFF","ON")
SKIP

Learning from command window is a pleasure reserved only for VFP!. It's also a good approach when debugging, or shopping for design ideas or workarounds.