You'll need change javascript function 'doExport' (native search_filter.js) putting it in file $NX_ROOT/site/mods/www/wwwroot/scripts/sitemods.js
Is required clear the browser cache to apply these changes.
function doExport(factory) {
alert('this is a test');
ImgBtnDisableButton("btnExport");
var href_str = window.document.location.href;
var start_pos = href_str.indexOf("://", 0) + "://".length;
var end_pos = href_str.indexOf("/", start_pos);
var target_url = href_str.substring(0, end_pos) + cfgCgi +
"?SID=" + cfgSID +
"+FID=" + fid_generator() +
"+OP=LINK_WITH_BOPSID+KEEP_ROLE=1" +
"+CALLBACK=export_cb('" + factory + "','" + nx_escape("%") + "bopsid')";
SyncAjaxJSCall(target_url);
var servletURLtoUse = ahdtop.cfgLocalServletURL;
var localHost = ahdtop.cfgLocalHost;
if ( typeof servletURLtoUse == "string" && servletURLtoUse.length > 0 &&
typeof localHost == "string" && localHost.length > 0)
if (servletURLtoUse != localHost)
window.setTimeout("ImgBtnEnableButton('btnExport')", 2500);
}