C#

public partial class NewTopicCtxCfgElemFrm : Form
  {
    private bool _freeConfig = false;

    public NewTopicCtxCfgElemFrm()
    {
      InitializeComponent();
    }

    public void Initialize(Topic topic)
    {
      _freeConfig = business.TopicFactory.GetTopicTypeIsFreeConfigurable(topic.ID);
      label1.Text = (_freeConfig) ? "Please select at least one of all." : "Please select all.";
      List<TopicTypeObjType> list = business.TopicFactory.GetObjTypeForTopic(topic.ID);
      int k = 0;
      foreach (var item in list)
      {
        int y = GetNewLocationTop(k);

        // add a label and a combobox to the form 
        Label lbl = new Label();
        lbl.Text = item.ObjTypeName;
        lbl.Location = new Point(10, y);
        lbl.Width = 200;
        this.Controls.Add(lbl);

        ComboBox cbx = new ComboBox();
        cbx.Location = new Point(220, y);
        cbx.Width = 200;
        cbx.Tag = item;
        this.Controls.Add(cbx);

        // set the datasource
        List<Xerox.CDMG.XControls.XDataItem> objects = business.ObjLinkFactory.GetObjForObjType(item.ObjTypeID);
        cbx.DataSource = objects;
        cbx.SelectedIndex = -1;

        // increment indexer
        k++;
      }
      // add an save-button to the form
      Button btn = new Button();
      btn.Text = "Save";
      btn.Location = new Point(10, GetNewLocationTop(k));
      btn.Width = 200;
      this.Controls.Add(btn);
      btn.Click += new EventHandler(btn_Click);
    }

    void btn_Click(object sender, EventArgs e)
    {
      try
      {
        bool checkRequiredObjTypesOk = !_freeConfig;
        // check if all required obj types are selected
        for (int i = 0; i < this.Controls.Count; i++)
        {
          Control cc = this.Controls[i];
          ComboBox cb = cc as ComboBox;
          if (cb != null)
          {
            if (!_freeConfig)
            {
              if (cb.SelectedIndex == -1) { checkRequiredObjTypesOk = false; }
            }
            else
            {
              if (cb.SelectedIndex > -1) { checkRequiredObjTypesOk = true; }
            }
          }
        }
      }
      catch (Exception exc)
      {
        Logger.LogException(exc);
      }
    }

    private int GetNewLocationTop(int k)
    {
      return k * 25 + label1.Top + label1.Height + 30;
    }

  }