Hello! I need to use Flash Player in IceCat on GNU GuixSD. First I tried to download NPAPI from get.adobe.com and to place it into ~/.mozilla/plugins with `chmod +x libflashplayer.so`. But after  Icecat restart, flash player plugin does not appear. Now I try to compile Gnash - GNU Flash alternative. I did not found it in repository: $ guix package -s gnash $ So I have downloaded and unzipped gnash-0.8.10. And try to compile as non-root user. I've installed boost for it , but gnash configure script does not find it: $ guix package -i boost The following package will be installed:    boost    1.66.0    /gnu/store/l6hqfwr1hcbn9rg56bwn2d41g2ai36h2-boost-1.66.0 substitute: updating list of substitutes from 'https://mirror.hydra.gnu.org '... substitute: updating list of substitutes from 'https://mirror.hydra.gnu.org '... 100.0% ... 73 packages in profile $ whereis boost boost: $ ls /gnu/store/l6hqfwr1hcbn9rg56bwn2d41g2ai36h2-boost-1.66.0 include/  lib/  share/ $ pwd /home/bob/Downloads/gnash-0.8.10 $ ./configure ... checking whether pthreads work with -pthread... yes checking searching for pthread library... not found checking for the Boost Version... checking for boost header... checking for Boost libraries... configure: WARNING: Libraries  thread program_options iostreams  serialization date_time aren't installed checking if -fvisibility-inlines-hidden is broken... no checking whether g++ supports -fvisibility=hidden... yes checking whether GConf support is requested... yes checking for GCONF... configure: error: Package requirements (gconf-2.0) were not met. Consider adjusting the PKG_CONFIG_PATH environment variable if you installed software in a non-standard prefix. Alternatively you may set the GCONF_CFLAGS and GCONF_LIBS environment variables to avoid the need to call pkg-config.  See the pkg-config man page for more details. -- Please, what to do?