Synfig Studio 2D animation software Gtk3 on Ubuntu 15.04 linux
http://www.synfig.org/cms/en/news/new...
Interface migrated to Gtk3
Various UI improvements
Improved Bone Distortion
Various fixes for Brushes feature
Sound playback for Preview Dialog
HSV color wheel and improved SpriteSheet export
Synfig Studio is a free and open-source 2D animation software, designed as powerful industrial-strength solution for creating film-quality animation using a vector and bitmap artwork. It eliminates the need to create animation frame-by frame, allowing you to produce 2D animation of a higher quality with fewer people and resources. Synfig Studio is available for Windows, Linux and MacOS X.