Dim instance As TabBrowser = New TabBrowser()
Dim value As System.Windows.Forms.WebBrowser

instance.WebBrowser = value
value = instance.WebBrowser

'TabBrowserクラス WebBrowserプロパティ

Imports System.Windows.Forms

Public Class AddIn

    Private tabb As TabBrowser

    Public Sub New()
        tabb = New TabBrowser()
        tabb.DocumentCompletedEventAdd(AddressOf documentCompleted)
        tabb.Navigate("http://www.google.com/")
    End Sub

    Public Sub documentCompleted(ByVal sender As Object, ByVal e As System.EventArgs)
        tabb.DocumentCompletedEventRemove(AddressOf documentCompleted)
        MessageBox.Show(tabb.WebBrowser.DocumentTitle)
    End Sub

End Class