Sorry to post here but I don't see any Graphical installers bug report section on your site. My problem is related to the Graphical installers program to install XFCE 4.4, I've downloaded the program, make it executable and run it as super user root on my TWM environment via xterm terminal, the installer find all dependencies and started correctly but my problem is related to characters not displaying at all! I can only see square  in place of English character for example. This make me impossible to continue the installation on my Linux OS because I cannot read what is on the screen. I suspect locale setting to be in cause.
The graphical installer relies on gtk+ and other libs to render fonts, so I doubt this is an issue with the installer.
Can you give some more informations on the system you're installing?
I found the problem to be related to cairo and pango. I forget to generate the /etc/pango/pango.modules file used for type. Once generated, I was able to see characters on the GUI Installer.