I'm not sure how many folks here are fans of Google's Go language, but there are some up-and-coming GTK bindings for the language (http://github.com/conformal/gotk3) that make application development smooth like Python, but performant like C or Vala.
GTK+ 3.x is (finally) available on Windows through DLL bundles, automatically built on GNOME servers. We also have the beginnings of a continuous integration build, so that you can always easily test the latest Git snapshots.
Many thanks to Manuel Bachmann, who did all the work on the build environment; and Andrea Veri, who set up the infrastructure.
GTK+, or the GIMP Toolkit, is a multi-platform toolkit for creating graphical user interfaces. Offering a complete set of widgets, GTK+ is suitable for projects ranging from small one-off tools to complete application suites.
GTK+ can be used from multiple platforms and operating systems.
GTK+ is written in C but has been designed from the ground up to support a wide range of languages, not only C/C++. Using GTK+ from languages such as Perl and Python (especially in combination with the Glade GUI builder) provides an effective method of rapid application development.