Clutter

Clutter is an open source (LGPL 2.1) software library for creating fast, compelling, portable, and dynamic graphical user interfaces.

It is a core part of MeeGo, and is supported by the open source community. Clutter uses OpenGL for rendering (and optionally OpenGL|ES for use on mobile and embedded platforms), but wraps an easy to use, efficient, flexible API around GL's complexity.