Debate at the capitol today about financing for a new Vikings stadium on the Metrodome site in downtown Minneapolis.  A State Senate committee approved an amendment directing the Metropolitan Sports Facilities Commission and the Vikings to make recommendations on the design and financing of a new stadium.  Funding for the 2-million-dollar study would be split by the team and the commission. Sports Facilities Commission Chairman Roy Terwilliger said the design envisions a RETRACTABLE roof.  Roseville DFLer John Marty voted AGAINST the amendment, saying it presumes that public money is needed for a new stadium.  The study would be completed by January of 2009, in time for a full fledged stadium debate in the next legislative session.  The Vikings Metrodome lease expires after the 2011 season.