How to populate another page item based on cascading select lists?

Question

Oracle 10gXE
APEX 3.2
I've created cascading select lists based on the examples (using Javascript and AJAX) that i've seen on this forum. Thanks for help on that!
Now that I have these LOV's being populated without needing to submit the page, how do I take the value that is presently in each LOV and concatenate them together to populate another page item? I'm trying to build the URL string that will execute an Oracle Report once the user clicks a button.
Previously, when I had multiple Select Lists with a submit, the URL was being put together using an After Submit Computation that would set the value for an item (P26_REPORT_URL) on the page. Notice that a report parameter (i.e. parameter name and Select List value) is only included if the user has provided a value. The page item that holds these values is then referenced by a button for URL redirect. The URL Target for the button currently is: javascript:popupURL('&P26_REPORT_URL.'), but will not work at the moment because P26_REPORT_URL page item is not changing based on what is selected in the LOVs. Since I'm not submitting anything (do I need to?), how do I put together the values needed?
Computation for P26_REPORT_URL:
DECLARE
l_param VARCHAR2(2000);
BEGIN
l_param := '&REPORTS_URL.&report=&P26_RPT_VIEW..rdf&desformat=&P26_DESFORMAT.&destype=cache';
IF REPLACE(:P26_OLO_CODE,'%'||'null%',NULL) IS NOT NULL THEN
l_param := l_param||'&p_olo_code=&P26_OLO_CODE.';
END IF;
IF REPLACE(:P26_BEG_DATE,'%'||'null%',NULL) IS NOT NULL THEN
l_param := l_param||'&p_start_dt=&P26_BEG_DATE.';
END IF;
IF REPLACE(:P26_END_DATE,'%'||'null%',NULL) IS NOT NULL THEN
l_param := l_param||'&p_end_dt=&P26_END_DATE.';
END IF;
IF REPLACE(:P26_ORG_CODE_2,'%'||'null%',NULL) IS NOT NULL THEN
l_param := l_param||'&p_org_code=&P26_ORG_CODE_2.';
END IF;
IF REPLACE(:P26_FLAIR_ORG_2,'%'||'null%',NULL) IS NOT NULL THEN
l_param := l_param||'&p_flair_org_code=&P26_FLAIR_ORG_2.';
END IF;
IF REPLACE(:P26_BUDGET_ENTITY_2,'%'||'null%',NULL) IS NOT NULL THEN
l_param := l_param||'&p_agy_code=&P26_BUDGET_ENTITY_2.';
END IF;
RETURN l_param;
END;

Answer 1

Andy,
This is a great suggestion! After I posted, I started looking at a Javascript solution and figured it's probably what I had to do.
However, now the cascading select list no longer working for some reason after I added the function to concatenate the item values. When I remove the showReport() function the select list works again.
Here is what I have in the HTML Header portion of the page:
<script language="JavaScript" type="text/javascript">
function popupURL (url) {
  w = open(url,"winLov","resizable=1,width=800,height=600");
  if (w.opener == null)
  w.opener = self;
  w.focus();
function showReport()
  var l_param = '&REPORTS_URL.&report=' + $v('P26_RPT_VIEW') + '.rdf&desformat=' + $v('P26_DESFORMAT') + '&destype=cache';
  if ($v('P26_OLO_CODE' != '')
   l_param += '&p_olo_code=' + $v('P26_OLO_CODE');
  if ($v('P26_ORG_CODE_3' != '')
   l_param += '&p_org_code=' + $v('P26_ORG_CODE_3');
  popupURL(l_param);
  function get_AJAX_SELECT_XML(pThis,pSelect){  
     var l_Return = null; 
     var l_Select = $x(pSelect); 
     var get = new htmldb_Get(null,$x('pFlowId').value,'APPLICATION_PROCESS=ORG_SELECT_LIST',0); 
     get.add('TEMPORARY_ITEM',pThis.value); 
     gReturn = get.get('XML'); 
     if(gReturn && l_Select){ 
         var l_Count = gReturn.getElementsByTagName("option").length; 
         l_Select.length = 0;
         for(var i=0;i<l_Count;i++){ 
             var l_Opt_Xml = gReturn.getElementsByTagName("option");
appendToSelect(l_Select, l_Opt_Xml.getAttribute('value'), l_Opt_Xml.firstChild.nodeValue)
get = null;
function appendToSelect(pSelect, pValue, pContent) { 
var l_Opt = document.createElement("option");
l_Opt.value = pValue;
if(document.all){
pSelect.options.add(l_Opt);
l_Opt.innerText = pContent;
}else{ 
l_Opt.appendChild(document.createTextNode(pContent));
pSelect.appendChild(l_Opt);
</script>