#include <GUIConstantsEx.au3>
#include <GuiTreeView.au3>
#include <MsgBoxConstants.au3>
#include <WindowsConstants.au3>

Example()

Func Example()
        GUICreate("TreeView Get Count (v" & @AutoItVersion & ")", 400, 300)

        Local $iStyle = BitOR($TVS_EDITLABELS, $TVS_HASBUTTONS, $TVS_HASLINES, $TVS_LINESATROOT, $TVS_DISABLEDRAGDROP, $TVS_SHOWSELALWAYS, $TVS_CHECKBOXES)
        Local $idTreeView = GUICtrlCreateTreeView(2, 2, 396, 268, $iStyle, $WS_EX_CLIENTEDGE)
        GUISetState(@SW_SHOW)

        _GUICtrlTreeView_BeginUpdate($idTreeView)
        Local $idItem
        For $x = 0 To 15
                $idItem = GUICtrlCreateTreeViewItem(StringFormat("[%02d] New Item", $x), $idTreeView)
                For $y = 0 To 2
                        GUICtrlCreateTreeViewItem(StringFormat("[%02d] New Item", $y), $idItem)
                Next
        Next
        _GUICtrlTreeView_EndUpdate($idTreeView)

        MsgBox($MB_SYSTEMMODAL, "Information", "Count: " & _GUICtrlTreeView_GetCount($idTreeView))

        ; Loop until the user exits.
        Do
        Until GUIGetMsg() = $GUI_EVENT_CLOSE
        GUIDelete()
EndFunc   ;==>Example