Sub ccc()
Dim bk As Workbook
Dim w As Window
If Workbooks.Count = 0 Then
 'none open
  MsgBox "Open a workbook"
  Exit Sub
Else
 ' check for any visible
 bVisible = False
 For Each bk In Workbooks
   For Each w In bk.Windows
      Debug.Print w.Caption, w.Visible
      If w.Visible = True Then
       
        bVisible = True
      End If
    Next
 Next
End If
if bVisible = false then
 msgbox "Open a workbook"
 exit sub
End if
' more code
End Sub