I find it quite unfortunate that current releases of Firebird & Thunderbird require different versions of glibc - glibc 2.2.4 for the former, glibc 2.3.2 for the latter. I really would like to use Thunderbird, but I have better things to do in life than track down & download library upgrades, esp when my 3 yr old install is otherwise running just fine.
I would much appreciate the developers taking a little more conservative approach when identifying their target configuration.