the SDL demo has lots of dependencies obviously, so it's really not something self-contained. I'm always excited any neat GUI for C, but this one seems like just a layer on top of existing GUI libraries, what's special about it? Please shed some light.

If it's really light-weight and self-contained it will be very useful for some embedded systems with a screen.

$ldd bin/demo
linux-vdso.so.1 => (0x00007fff46f49000)
libSDL2-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0 (0x00007f3587140000)
libGL.so.1 => /usr/lib/fglrx/libGL.so.1 (0x00007f3586f5e000)
libGLEW.so.1.6 => /usr/lib/x86_64-linux-gnu/libGLEW.so.1.6 (0x00007f3586cf2000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3586934000)
libasound.so.2 => /usr/lib/x86_64-linux-gnu/libasound.so.2 (0x00007f3586647000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f358634a000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f3586146000)
libpulse-simple.so.0 => /usr/lib/x86_64-linux-gnu/libpulse-simple.so.0 (0x00007f3585f42000)
libpulse.so.0 => /usr/lib/x86_64-linux-gnu/libpulse.so.0 (0x00007f3585cf9000)
libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f35859c4000)
libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007f35857b3000)
libXcursor.so.1 => /usr/lib/x86_64-linux-gnu/libXcursor.so.1 (0x00007f35855a8000)
libXinerama.so.1 => /usr/lib/x86_64-linux-gnu/libXinerama.so.1 (0x00007f35853a5000)
libXi.so.6 => /usr/lib/x86_64-linux-gnu/libXi.so.6 (0x00007f3585195000)
libXrandr.so.2 => /usr/lib/x86_64-linux-gnu/libXrandr.so.2 (0x00007f3584f8c000)
libXss.so.1 => /usr/lib/x86_64-linux-gnu/libXss.so.1 (0x00007f3584d88000)
libXxf86vm.so.1 => /usr/lib/x86_64-linux-gnu/libXxf86vm.so.1 (0x00007f3584b83000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f3584965000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f358475d000)
libatiuki.so.1 => /usr/lib/fglrx/libatiuki.so.1 (0x00007f3584640000)
/lib64/ld-linux-x86-64.so.2 (0x00007f3587469000)
libpulsecommon-1.1.so => /usr/lib/x86_64-linux-gnu/libpulsecommon-1.1.so (0x00007f35843e1000)
libjson.so.0 => /usr/lib/x86_64-linux-gnu/libjson.so.0 (0x00007f35841d9000)
libdbus-1.so.3 => /lib/x86_64-linux-gnu/libdbus-1.so.3 (0x00007f3583f94000)
libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f3583d76000)
libXrender.so.1 => /usr/lib/x86_64-linux-gnu/libXrender.so.1 (0x00007f3583b6c000)
libXfixes.so.3 => /usr/lib/x86_64-linux-gnu/libXfixes.so.3 (0x00007f3583965000)
libwrap.so.0 => /lib/x86_64-linux-gnu/libwrap.so.0 (0x00007f358375c000)
libsndfile.so.1 => /usr/lib/x86_64-linux-gnu/libsndfile.so.1 (0x00007f35834f5000)
libasyncns.so.0 => /usr/lib/x86_64-linux-gnu/libasyncns.so.0 (0x00007f35832ef000)
libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007f35830ec000)
libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007f3582ee5000)
libnsl.so.1 => /lib/x86_64-linux-gnu/libnsl.so.1 (0x00007f3582ccb000)
libFLAC.so.8 => /usr/lib/x86_64-linux-gnu/libFLAC.so.8 (0x00007f3582a81000)
libvorbisenc.so.2 => /usr/lib/x86_64-linux-gnu/libvorbisenc.so.2 (0x00007f35825b1000)
libvorbis.so.0 => /usr/lib/x86_64-linux-gnu/libvorbis.so.0 (0x00007f3582385000)
libogg.so.0 => /usr/lib/x86_64-linux-gnu/libogg.so.0 (0x00007f358217e000)
libresolv.so.2 => /lib/x86_64-linux-gnu/libresolv.so.2 (0x00007f3581f61000)