URL Filtering and XWiki License

Hi, I´m part of a development team that is trying to get XWIKI working as a jsr168 portlet, to integrate it in a commercial portal. We have been able to run it on Jetspeed-2 without major problems, except for URLs. It seems that Portlet URLs are generated and then filtered that causes some major bugs in urls within the portlet since a url ending with 2 underscores ( ..../...__/ ). Has this problem been submitted before? I´ve looked in Jira but didn´t found nothing related to it. Is there any information on where to start digging or changes adviced, without changing the normal flow of xwiki? What should/must be done, if possible, to integrate the xwiki to that commercial portal, according to your requirements? Another issue is that any changes to XWiki Core must be delivered to the project according to the License, is that valid also for skins developed? Thanks in advance Ricardo Esquito. ps -> sorry for the bad english :-s