private void buttonHistory_Click(object sender, RoutedEventArgs e)
{
RevisionHistoryDialog revDia = new RevisionHistoryDialog();
revDia.DocumentName = Session.GetInstance().CurrentDocumentTitle;
revDia.EditorName = "";
revDia.Revisions = controller.GetAllDocumentRevisionsWithContent(Session.GetInstance().CurrentDocumentID);
revDia.CreateTreeView();
revDia.ShowDialog();
}