sudo apt-get install libsfml-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libsfml-dev : Depends: libgl1-mesa-dev but it is not going to be installed or
                        libgl-dev
               Depends: libglu1-mesa-dev but it is not going to be installed or
                        libglu-dev
E: Unable to correct problems, you have held broken packages.
klez@phobos:~/software$ sudo aptitude install libsfml-dev
The following NEW packages will be installed:
  libdrm-dev{ab} libgl1-mesa-dev{ab} libglu1-mesa-dev{a} libopenal-data{a} libopenal1{a} libsfml-audio2{a} libsfml-dev libsfml-graphics2{a} libsfml-network2{a}
  libsfml-system2{a} libsfml-window2{a} libx11-xcb-dev{a} libxcb-dri2-0-dev{a} libxcb-dri3-dev{a} libxcb-glx0-dev{a} libxcb-present-dev{a} libxcb-randr0-dev{a}
  libxcb-render0-dev{a} libxcb-shape0-dev{a} libxcb-sync-dev{a} libxcb-xfixes0-dev{a} libxdamage-dev{a} libxext-dev{a} libxfixes-dev{a} libxshmfence-dev{a}
  libxxf86vm-dev{a} mesa-common-dev{a} x11proto-damage-dev{a} x11proto-dri2-dev{a} x11proto-fixes-dev{a} x11proto-gl-dev{a} x11proto-xext-dev{a}
  x11proto-xf86vidmode-dev{a}
0 packages upgraded, 33 newly installed, 0 to remove and 0 not upgraded.
Need to get 2,050 kB of archives. After unpacking 9,592 kB will be used.
The following packages have unmet dependencies:
 libgl1-mesa-dev : Depends: libgl1-mesa-glx (= 10.3.2-1+deb8u1) but 13.0.6-1~bpo8+1 is installed.
 libdrm-dev : Depends: libdrm2 (= 2.4.58-2) but 2.4.74-1~bpo8+1 is installed.
              Depends: libdrm-intel1 (= 2.4.58-2) but 2.4.74-1~bpo8+1 is installed.
              Depends: libdrm-radeon1 (= 2.4.58-2) but 2.4.74-1~bpo8+1 is installed.
              Depends: libdrm-nouveau2 (= 2.4.58-2) but 2.4.74-1~bpo8+1 is installed.
The following actions will resolve these dependencies:

     Keep the following packages at their current version:
1)     libdrm-dev [Not Installed]
2)     libgl1-mesa-dev [Not Installed]
3)     libglu1-mesa-dev [Not Installed]
4)     libsfml-dev [Not Installed]
5)     mesa-common-dev [Not Installed]