private void showSampleTreeButton_Click(object sender, EventArgs e)
        {
            SymbolicExpressionGrammarSampleExpressionTreeView view = new SymbolicExpressionGrammarSampleExpressionTreeView();

            view.Content = Content;
            view.Show();
        }
 private void showSampleTreeButton_Click(object sender, EventArgs e) {
   SymbolicExpressionGrammarSampleExpressionTreeView view = new SymbolicExpressionGrammarSampleExpressionTreeView();
   view.Content = Content;
   view.Show();
 }