Private Type RECT
        Left As Long
        Top As Long
        Right As Long
        Bottom As Long
End Type

Private Const BLACK_BRUSH =  4 

Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
 (ByVal hWnd1 As Long, ByVal hWnd2 As Long, _
  ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
Private Declare Function GetNextWindow Lib "user32" Alias "GetWindow" _
 (ByVal hwnd As Long, ByVal wFlag As Long) As Long
Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hDC As Long) As Long
Private Declare Function FrameRect Lib "user32" (ByVal hDC As Long, lpRect As RECT, ByVal hBrush As Long) As Long
Private Declare Function GetStockObject Lib "gdi32" (ByVal nIndex As Long) As Long

Private Sub Кнопка0_Click()
    Dim hDetailHWND As Long, hDC As Long, r As RECT, i As Long, hBrush As Long
    
    hDetailHWND = GetNextWindow(FindWindowEx(Me.hwnd,  0 , "OFormSub", vbNullString),  2 )
    hDC = GetDC(hDetailHWND)
    hBrush = GetStockObject(BLACK_BRUSH)
    
    r.Left =  0 : r.Top =  0 : r.Right =  50 : r.Bottom =  50 
    For i =  1  To  20 
        r.Left =  5  * i: r.Right =  5  * i +  50 
        r.Top =  5  * i: r.Bottom =  5  * i +  50 
        FrameRect hDC, r, hBrush
    Next
 
    ReleaseDC hDetailHWND, hDC
End Sub