I installed GTK+ 3.22, but by doing so I managed to break my system completely for a while. I had to resort to recovery mode and to deleting all libraries related to GTK and then run apt-get purge libgtk+3.0 && apt-get install libgtk+3.0.After that I managed to enter lightdm and log in, but I had absolutely no icons. All GTK applications had no icons and were generating lots of warnings. I figured it is a gdk-pixbuff problem since the errors were all saying something about that library, so I purged and installed libgdk-pixbuf2.0. This fixed the icons issue, but still some of my apps give me warnings about missing icons. Now I have font problems, in the sense that the fonts look horrible and I cannot launch any Cocos2d-x application due to the fact that the library relies on GTK. The error says that it cannot find the file fontconfig/fontconfig.h. As a result I looked in /usr/local/includes to find out there really is no fontconfig.h. I tried purging fontconfig, but the system won't let me and gives me the following error:Some packages could not be installed. This may mean that you haverequested an impossible situation or if you are using the unstabledistribution that some required packages have not yet been createdor been moved out of Incoming.The following information may help to resolve the situation:The following packages have unmet dependencies: emacs : Depends: emacs24 or                  emacs24-lucid but it is not going to be installed or                  emacs24-nox but it is not going to be installedE: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.My question is, how can I reinstall fontconfig properly together with all header files?
How to fix gtk dependencies?
gtk3;fontconfig
apt-file will tell you (install it if you don't have it already):$ apt-file search fontconfig/fontconfig.hlibfontconfig1-dev: /usr/include/fontconfig/fontconfig.hSoapt-get --reinstall install libfontconfig1-devshould restore fontconfig/fontconfig.h.