processmaker-files/workflow/engine/xmlform/groups/groups_AddUser.xml

<?xml version="1.0" encoding="UTF-8"?>
<dynaForm type="xmlform" width="95%">
  <title type="title" colWidth="200" showInTable="0">
    <en><![CDATA[User]]></en>
  </title>
  <USR_UID type="dropdown" colWidth="200">
  SELECT USR_UID, USR_USERNAME FROM USERS
  <en><![CDATA[User]]></en>
</USR_UID>
  <GRP_UID type="hidden"/>
  <button type="button" onclick="saveUserGroup( this.form );" showInTable="0">
    <en><![CDATA[Accept]]></en>
  </button>
</dynaForm>