private void btn_Add_Click(object sender, RoutedEventArgs e)
{
GroupBox groupBox = new GroupBox {
Height = 500, Width = 400
};
StackPanel stackPanel = new StackPanel();
TextBlock textBlock = new TextBlock();
TextBox textBox = new TextBox();
groupBox.Header = "Question #1";
groupBox.Style = (Style)groupBox.FindResource("MaterialDesignCardGroupBox");
textBlock.Text = "TextBlock";
textBox.Width = 200;
textBox.Height = 30;
stackPanel.Children.Add(textBlock);
stackPanel.Children.Add(textBox);
groupBox.Content = stackPanel;
this.grid.Children.Add(groupBox);
}