In the process of switching my folks over to TFS 2012, I was evaluating the team project reports I moved over. When I double-clicked on a report to open it, instead of seeing it in a tab within my VS 2012 IDE, it opens in a separate web browser window.
This behavior exhibits in migrated team projects (from 2010 to 2012), as well as newly created team projects. I'm inclined to think it's a configuration issue missed on my part, but I can't seem to nail it down.
[Migration details: upgrade performed by detaching 2010 collection, reattaching to running instance of TFS2012 on new hardware. ReportServer database was moved separately. Hardware is all WinSrv2008R2, SQL2012 Standard.]
UPDATE: altered title as this is happening to any/all settings and controls, as well, for any given team project (Security, Group Membership, Work Item Areas, etc). Anything that is URL-based. So, at least it's misbehaving consistently.