Some js note For the disable and enable the combox

 
	<select class="form1" id="symbol"  onbeforeactivate="return false"   onmouseover="this.setCapture()" onmouseout="this.releaseCapture()" onchange="getSecurityName()" name="symbol.displayValue">
								<option selected value=""></option>
								<option  value="ISIN">ISIN</option>
								<option  value="CUSP">CUSP</option>
								<option  value="SEDL">SEDL</option>
							<option  value="QUIK">QUIK</option>
		</select>	

 selectBox.attachEvent("onbeforeactivate", function(){return true;});
					        selectBox.attachEvent("onmouseover", function(){document.getElementById('symbol').releaseCapture();});

document.getElementById('cusip').setAttribute('readOnly', ''); 
document.getElementById('region').style.visibility = "visible";