I had to install pd-extended on a Ubuntu Lucid box and the .deb listed in the download section still has a tk8.4 dependency, which in turns seems to give a font problem [1]? I downloaded the source tar.gz from the same page, compiled with the autobuild script and the generated deb doesn't have the dependecy any more.
Lorenzo.
[1] See: http://lists.puredata.info/pipermail/pd-list/2010-12/085104.html