Checking on my installation, I think your gnunet-gtk errors come from the fact that you have an ancient custom installation in /usr/local. Removing /usr/local/bin/gnunet* and /usr/local/lib/libgnunet*, /usr/local/lib/GNUnet/ should help.
Checking on my installation, I think your gnunet-gtk errors come from the fact that you have an ancient custom installation in /usr/local. Removing /usr/local/ bin/gnunet* and /usr/local/ lib/libgnunet* , /usr/local/ lib/GNUnet/ should help.