We need some tweak/customization in the "ewp.js" template file in order to display the "caption" param of "ew_ModalDialogShow" function.
See this code in "ewp.js" template file:
$dlg.find(".modal-title").html($lnk.data("caption") || $lnk.data("original-title"));
We need it to be customized/changed become:
$dlg.find(".modal-title").html(args.caption $lnk.data("caption") $lnk.data("original-title"));
If we do not change it, then this code (for example):
ew_ModalDialogShow({lnk: this, url: 'orderdetailsadd.php', caption: 'Search'});
will NOT display "Search" in modal dialog title section. After customize the code above, then the "Search" caption will be displayed properly in modal dialog title.