GNOME Bugzilla – Bug 669140
Mac OS X DMG: SVG images cannot be inserted into diagrams (and no Gradient shapes)
Last modified: 2012-03-21 18:16:07 UTC
Reported on the mailing list. Confirmed with the current 0.97.2 build and DMG.
http://trac.macports.org/ticket/33616/
Fixed in MacPorts and the new 0.97.2-3 DMG available from http://dia-installer.de/download/macosx.html