Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function ShowWindow Lib "user32" Alias "ShowWindowAsync" (ByVal hwnd As Long, ByVal nCmdShow As Long) As Long
Private Declare Function SetWindowPos Lib "user32" (ByVal hwnd As Long, ByVal hWndInsertAfter As Long, ByVal X As Long, ByVal Y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long

Dim hwnd1, hwnd2
Const SWP_NOMOVE =  2 
Const SWP_NOSIZE =  1 
Const HWND_TOPMOST = - 1 
Const HWND_NOTOPMOST = - 2 
Const SW_SHOW =  5 
Const SW_HIDE =  0 

Private Sub Command1_Click()
    hwnd1 = FindWindow("XLMAIN", vbNullString)
    hwnd2 = FindWindow("bosa_sdm_XL9", vbNullString)
ShowWindow hwnd1, SW_HIDE
SetWindowPos hwnd2, HWND_TOPMOST,  0 ,  0 ,  0 ,  0 , SWP_NOMOVE + SWP_NOSIZE
End Sub

Private Sub Command2_Click()
ShowWindow hwnd1, SW_SHOW
SetWindowPos hwnd2, HWND_NOTOPMOST,  0 ,  0 ,  0 ,  0 , SWP_NOMOVE + SWP_NOSIZE
End Sub