wxWidgets lets developers create applications for Win32, Mac OS X, GTK+, X11, Motif, WinCE, and more using one codebase. It can be used from languages such as C++, Python, Perl, and C#/.NET. wxWidgets applications look and feel native.
The resizeable board is implemented with the Gtk2Hs GUI Library for Haskell based on Gtk and the included Cairo 2d graphics library support. The pieces are hand created<sep/>
"wxAUI is an Advanced User Interface library that aims to implement "cutting-edge" interface usability and design features so developers can quickly and easily create beautiful and usable application interfaces."