Create Custom DropList In Sitecore WFFM

Sample code for custom DropDownList in WFFM.

public class CustomDropListStateProvPicker : Sitecore.Form.Web.UI.Controls.DropList
    {
        private string _initiallySelectedStateProv;

        [VisualCategory("Initial Selection")]
        [VisualFieldType(typeof(TextAreaField)), Localize]
        [VisualProperty("Initial Selection:", 100)]
        public string InitialSelection { get; set; }

        protected override void InitItems(Sitecore.Form.Web.UI.Controls.ListItemCollection items)
        {
            this.KeepHiddenValue = false;

            items = new Sitecore.Form.Web.UI.Controls.ListItemCollection();

            OrderedDictionary dictionaryStateProvs = GetStateProvs();

            foreach (DictionaryEntry stateprov in dictionaryStateProvs)
            {
                items.Add(new ListItem() { Value = (string)stateprov.Key, Text = (string)stateprov.Value });

                if ((string)stateprov.Value == InitialSelection)
                {
                    _initiallySelectedStateProv = (string)stateprov.Key;
                }
            }
            base.InitItems(items);
        }

        protected override void DoRender(HtmlTextWriter writer)
        {
            if (!string.IsNullOrEmpty(_initiallySelectedStateProv))
            {
                droplist.SelectedValue = _initiallySelectedStateProv;
            }
            base.DoRender(writer);
        }

        private OrderedDictionary GetStateProvs()
        {
            // Your custom logic for state binding.
            return dictionaryStateProvs;
        }
    }