After moving the libpng 1.6 rebuilds to [testing], I noticed that some PNG icons wouldn't load. In my case the broken icons belonged to nm-applet and smplayer (both have been fixed in [extra]). Some KDE components are probably affected but I'm not sure of the extend there. The plan is to run a check on the source files of all packages to better assess the situation. (pngchecker.py can be used for that.¹) It's not clear whether future libpng 1.6.x versions will be able to load these, apparently invalid, PNG images.² Running optipng (which is statically compiled against libpng 1.4) seems to fix the problematic PNG files. I have used this workaround in smplayer.³ More information can be found in Gentoo's discussion about this issue: http://www.gossamer-threads.com/lists/gentoo/dev/271064 ¹ https://bugs.gentoo.org/show_bug.cgi?id=466190#c11 ² https://bugzilla.mozilla.org/show_bug.cgi?id=841734#c3 ³ https://projects.archlinux.org/svntogit/packages.git/commit/trunk?h=packages/smplayer&id=83c83d34c8872cd29ee256a5485e64f87814fc43