7
open include/registerform.php
and add 'true' to the end of the fields you want required
ie..
to make the url field required
change (line 73):
$reg_form->addElement(new XoopsFormText(_US_WEBSITE, "url", 25, 255, $myts->htmlSpecialChars($url)));
to
$reg_form->addElement(new XoopsFormText(_US_WEBSITE, "url", 25, 255, $myts->htmlSpecialChars($url)), true);
and so on for each field.
for the edit user page do the same in file edituser.php
$edituser->setVar('url', formatURL($_POST['url']));
change to
$edituser->setVar('url', formatURL($_POST['url']), true);