Disabling an Add-in ComboBox

[DaveCouture]

I created a VB.NET Add-In tool that adds layers to the map, from a Layer List ComboBox.  Everything works fine, but I do not want the tool to work when in Layout View. I know how to verify if I'm in the Layout View and display a message, but I would like to disable the ComboBo, instead of a message box. How can I modify my code to accomplish this?

        If TypeOf My.ArcMap.Document.ActiveView Is IPageLayout Then
            MsgBox("Switch to Data View to run the tool")
            Return
        End If

[KenBuja]

** wrong reply **

[DaveCouture]

Finally found the answer here: http://help.arcgis.com/en/sdk/10.0/arcobjects_net/conceptualhelp/index.html#//0001000000zz000000

I have to use the Update() method. This is my code:

   
    Protected Overloads Overrides Sub OnUpdate()
        ' Disabled if in Layer View
        If TypeOf My.ArcMap.Document.ActiveView Is IPageLayout Then
            Me.Enabled = False
        ElseIf TypeOf My.ArcMap.Document.ActiveView Is IMap Then
            Me.Enabled = True
        End If
    End Sub

[RichardMoussopo]

Hi, is there a way you can share the code that adds the layers in your combobox please? Also how can you make the combobox selects by default the first layer in the list?