The binary package libswt-gtk3-jni 3.0-6 is in the main Debian stable archive. I suspect it might be an entirely non-functioning binary. Could you please test this binary by installing and running the package azureus 2.2.0.2-1 from contrib. If any graphics appear, the swt-gkt package works. If it crashes SIGSEGV, the package clearly doesn't work. Many thanks, Shaun