qt4-mac @4.7.4_1+quartz libpng error

[pcrackenberg@…]

I got a libpng error, as mentioned on the FAQ here: ​https://trac.macports.org/wiki/ProblemHotlist#libpng

This was the following error I got after installing py27-pyqt4 and the required dependencies:

Traceback (most recent call last):
  File "QtEvent.pyw", line 15, in <module>
    from PyQt4.QtGui import *
ImportError: dlopen(/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/PyQt4/QtGui.so, 2): Library not loaded: /opt/local/lib/libpng12.0.dylib
  Referenced from: /opt/local/lib/libQtGui.4.dylib
  Reason: image not found

Forcing an upgrade (as stated in the FAQ) for py27-pyqt4, python27, and libpng didn't work, however forcing an upgrade for qt4-mac fixed the problem.