Private Const TV_FIRST As Long = &H1100
Private Const TVM_GETNEXTITEM As Long = (TV_FIRST + 10)
Private Const TVM_DELETEITEM  As Long = (TV_FIRST + 1)
Private Const TVGN_ROOT As Long = &H0
Private Const WM_SETREDRAW As Long = &HB

Private Sub ClearTreeView(ByVal tv As TreeView)
    Dim tvHwnd As Long
    Dim lNodeHandle As Long
   
    tvHwnd = tv.hwnd
   
    SendMessageLong tvHwnd, WM_SETREDRAW, CLng(0), CLng(0)
   
    Do
        lNodeHandle = SendMessageLong(tvHwnd, TVM_GETNEXTITEM, TVGN_ROOT, CLng(0))
        If lNodeHandle > 0 Then
            SendMessageLong tvHwnd, TVM_DELETEITEM, CLng(0), lNodeHandle
        Else
            Exit Do
        End If
    Loop
   
    SendMessageLong tvHwnd, WM_SETREDRAW, CLng(1), CLng(0)
End Sub