From: http://sysadmin.wikia.com/wiki/Ubuntu
gsettings set com.canonical.indicator.datetime custom-time-format "'%F %H:%M'"
gsettings set com.canonical.indicator.datetime time-format "'custom'"
gsettings set com.canonical.indicator.datetime custom-time-format "'%F %H:%M'"
gsettings set com.canonical.indicator.datetime time-format "'custom'"
sudo aptitude install libx11-dev libmotif-dev libpng-dev \
libjpeg-dev libxt-dev x11proto-print-dev libxprintutil-dev \
libxprintapputil-dev libxcb-xprint0-dev libprinterconf-dev \
libxpm-dev
libxmu-dev