Kristian Rietveld is a long time contributor to GTK+. In the past he has contributed a lot of patches to GtkTreeView and GtkTreeModelSort, originally wrote GtkTreeModelFilter (and later actually made it work properly ;), the new combo box and entry completion and generally improved GTK+ by making the file chooser asynchronous and implementing a new tooltip system. During the last 4 years he focused on improving the port of GTK+ to Mac OS X.
Kris is currently a Computer Science Researcher and Lecturer in the Computer Systems group at LIACS, Leiden University. He holds a BSc and MSc in Computer Science from Leiden University.
You can reach Kris via kris (at) loopnest.org and follow him at https://twitter.com/krietvel/.