private void TG_Click(object sender, RoutedEventArgs e)
{
TreeGraph tg = new TreeGraph();
Text.Children.Clear();
Topics.Children.Add(tg);
}
private void Button_Click_4(object sender, RoutedEventArgs e)
{
Study st = new Study();
Block.Children.Clear();
AnotherPages.Children.Clear();
AnotherPages.Children.Add(st);
TreeGraph ql = new TreeGraph();
st.Text.Children.Clear();
st.Topics.Children.Add(ql);
}