Private Declare Function SendMessage Lib  "user32"  _
Alias  "SendMessageA"  (ByVal hWnd As Long, _
  ByVal wMsg As Long, ByVal wParam As Long, _
lParam As Long) As Long

Private Declare Function GetWindowLong Lib  "user32"  _
Alias  "GetWindowLongA"  (ByVal hWnd As Long, _
  ByVal nIndex As Long) As Long

Private Declare Function SetWindowLong Lib  "user32"  _
Alias  "SetWindowLongA"  (ByVal hWnd As Long, _
  ByVal nIndex As Long, _
  ByVal dwNewLong As Long) As Long

Private Const GWL_STYLE = - 16 &
Private Const TVM_SETBKCOLOR =  4381 &
Private Const TVM_GETBKCOLOR =  4383 &
Private Const TVS_HASLINES =  2 &

Private TV As Control

Private Sub Button50_Click()
On Error GoTo Err_Button50_Click

Dim lngStyle As Long

Set TV = Me![ctlTV]

Call SendMessage(TV.hWnd, TVM_SETBKCOLOR, _
      0 , ByVal RGB( 0 ,  150 ,  0 ))

lngStyle = GetWindowLong(TV.hWnd, GWL_STYLE)

Call SetWindowLong(TV.hWnd, GWL_STYLE, _
     lngStyle - TVS_HASLINES)
   
Call SetWindowLong(TV.hWnd, GWL_STYLE, lngStyle)

Exit_Button50_Click:
    Exit Sub

Err_Button50_Click:
    MsgBox Err.Description
    Resume Exit_Button50_Click
    
End Sub