[Zope] a question about role

I defined a role intended to allow my students to read the source code. After I log in with this role, called 'friend', I was able to read the PythonScript source, but not DTMLs which would be rendered. Even though I can get around this by providing them with 'viewsource', I am wondering how I can make the management interface display the source of DTMLs, rather than the randered pages. Any help is most highly appreciated. cheers, Luby