Editing Select Button


Is there a way that i can edit a Form SELECT BUTTON ? I would like to select an item but also need the possibility to type in an option which can’t be selected.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
        <link href="../../../dhtmlx/Form/skins/dhtmlxform_dhx_terrace.css" rel="stylesheet" type="text/css">
      	<script src="../../../dhtmlx/Form/dhtmlxcommon.js"></script>
      	<script src="../../../dhtmlx/Form/dhtmlxform.js"></script>
         <script type="text/javascript">		 
			function initForm() {
				var formdata = [
					{type: "fieldset",label: "<span style='color:#CF2748;font-weight:bold;'>Test</span>",width:290,offsetLeft: 20,offsetTop: 10,list: [
						{type: "settings",position: "label-left"},
						{type: "select",name: "test_1",label: "Test 1:",inputWidth: 60,labelWidth: 93,options:[
							{text: "A", value: "1"},
							{text: "B", value: "2"},
							{text: "C", value: "3"}
						{type: "select",name: "test_2",label: "Test 2:",inputWidth: 60,labelWidth: 93,options:[
							{text: "D", value: "1"},
							{text: "E", value: "2"},
							{text: "F", value: "3"}
		 		var Form = new dhtmlXForm("formbox", formdata);
			function doOnLoad() {				

	<body onload="doOnLoad();">
        <div id="formbox"></div>

Thank you