In order to install dropline GNOME, download the PackageKit package which will then be used to download all remaining packages and install it into your system. Get the installer for each architectures:
Run these command to start the installation and download process:
# installpkg PackageKit-0.8.17-i686-3dl_install.txz
# pkcon refresh force
# pkcon install dropline
Kudos to Eugen Wissner (aka Belka), saxa and Bart Van Der Hall (aka Tyrael).