Sub FindDefaultNamespace()
   Dim cm As CodeModel
   cm = DTE.Solution.Projects.Item(1).CodeModel

   Dim ce As CodeElement
   Dim ct As CodeType = Nothing
   Dim defNameSpace As CodeNamespace
   For Each ce In cm.CodeElements
      If TypeOf ce Is CodeType Then
         ct = CType(ce, CodeType)
         defNameSpace = ct.Namespace
      End If
   Next

   If Not IsNothing(defNameSpace) Then
      MsgBox(defNameSpace.Name)
   End If
End Sub

' Macro editor
Sub FindAllClasses()
   Dim cm As CodeModel
   cm = DTE.Solution.Projects.Item(1).CodeModel

   ' Look for all the namespaces and classes in the 
   ' project.
   Dim list As String
   Dim ce As CodeElement
   For Each ce In cm.CodeElements
      If (TypeOf ce Is CodeNamespace) Or (TypeOf ce Is CodeClass) Then
         ' Determine whether that namespace or class 
         ' contains other classes.
         GetClass(ce, list)
      End If
   Next

   MsgBox(list)
End Sub

Sub GetClass(ByVal ct As CodeElement, ByRef list As String)
   ' ct could be a namespace or a class. Add it to the list
   ' if it is a class.
   If (TypeOf ct Is CodeClass) Then
      list &= ct.Name & ControlChars.CrLf
   End If

   ' Determine whether there are nested namespaces or classes that 
   ' might contain other classes.
   Dim aspace As CodeNamespace
   Dim ce As CodeElement
   Dim cn As CodeNamespace
   Dim cc As CodeClass
   Dim elements As CodeElements
   If (TypeOf ct Is CodeNamespace) Then
      cn = CType(ct, CodeNamespace)
      elements = cn.Members
   Else
      cc = CType(ct, CodeClass)
      elements = cc.Members
   End If

   For Each ce In elements
      If (TypeOf ce Is CodeNamespace) Or (TypeOf ce Is CodeClass) Then
         GetClass(ce, list)
      End If
   Next
End Sub