pgadmin3 1.16.1 has been released. Bumping the 1.16 ebuild works for me, but you might want to add a USE flag for --enable-databasedesigner. I did so locally, and the segfault in 1.16 mentioned in comment #3 of bug #434944 does not occur for me with 1.16.1.
Done, and done.
Actually, it's "--enable-databasedesigner", not "--enable-database-designer". The current tree ebuild builds successfully, but the database designer feature is not enabled.
Apologies, I typo'd my bug search. Someone already reported the above in bug #447206.