Collapse & Expand Code

When I use Visual Studio IDE to edit an XML file, I often come accross a big tree that is not easily to find my way out. So I start to collapse the expanded nodes. Unfortunately it might be very hard to do this.
So I was looking for a macro to do it and found the following macro which I attached a toolbar icon to it:

'' Toggle the current row and go down one line
   Sub ToggleOne()
       Dim cmd As String = "Edit.ToggleOutliningExpansion"
       Dim ts As TextSelection = DTE.ActiveDocument.Selection

       DTE.ExecuteCommand(cmd)
       ts.LineDown()

   End Sub