3 - the ruby programming language
5 - XML documents to save config files
7 - convert/identify from ImageMagick for thumbnails,
8 mplayer for videos manipulation
10 - ruby-gettext for i18n
12 - ruby-gtk2 for the GUI
14 - with a self widget, `GtkAutoTable', allowing to view the
15 thumbnails and edit captions while dynamically reordering
16 when main window resize
18 - with many keyboard shortcuts