The new libpng3 (1.2.5.0-1) renames libpng12-0-dev to libpng12-dev, which seems to be intentional on the part of the new maintainer. I have a number of kde development packages which depend on libpng12-0-dev, though, and so will be removed if I upgrade libpng3.
Transcript: Shuttle:/home/josh# apt-get -s install libpng3 Reading Package Lists... Done Building Dependency Tree... Done The following extra packages will be installed: libpng12-0 The following packages will be REMOVED: kdelibs4-dev kdesdk kspy libarts1-dev libartsc0-dev libpng12-0-dev libqt3-mt-dev The following held packages will be changed: libpng12-0 libpng3 2 packages upgraded, 0 newly installed, 7 to remove and 7 not upgraded. Remv kdesdk (4:3.1.1-1 Debian:unstable) Remv kspy (4:3.1.1-1 Debian:unstable) Remv kdelibs4-dev (4:3.1.1-1 Debian:unstable) Remv libartsc0-dev (1.1.1-2 Debian:unstable) Remv libarts1-dev (1.1.1-2 Debian:unstable) Remv libqt3-mt-dev (3:3.1.1-7 Debian:unstable) Remv libpng12-0-dev (1.2.5-11 ) Inst libpng3 (1.2.5.0-1 Debian:unstable) [] Inst libpng12-0 (1.2.5.0-1 Debian:unstable) Conf libpng12-0 (1.2.5.0-1 Debian:unstable) Conf libpng3 (1.2.5.0-1 Debian:unstable) Should I file any bugs? If so, against libpng3, or against the other packages? Thank you, Josh