A cross-platform GUI library
wxWidgets is a C++ library that lets developers create applications for Windows, Mac OS X, Linux and other platforms with a single code base. It has popular language bindings for Python, Perl, Ruby and many other languages, and unlike other cross-platform toolkits, wxWidgets gives applications a truly native look and feel because it uses the platform's native API rather than emulating the GUI. It's also extensive, free, open-source and mature.
wxSOAP is SOAP (Simple Object Access Protocol) library for wxWidgets
A cross-platform wxWindows class for running Ghostscript and manipulating the image it produces, plus an IDE/debugger for developing programs written in PostScript. For a PostScript debugger, there is now also an Eclipse plug-in - see http://thomas-fritsch.github.io/psdt/
This is a simple RFC 1459 compatible IRC library that uses the socket classes of wxWidgets.