wxWidgets is a C++ library that lets developers create applications for Windows, OS X, Linux and UNIX on 32-bit and 64-bit architectures as well as several mobile platforms including Windows Mobile, iPhone SDK and embedded GTK+. It has popular language bindings for Python, Perl, Ruby and many other languages. Unlike other cross-platform toolkits, wxWidgets gives its 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.
wxWidget 2.9.2 has been officially released in 2011-07-05 .It is available from the usual locations at SourceForge and FTP mirror. 2.9 series bring many improvements compared to 2.8 series such as much better Unicode support and the new wxOSX/Cocoa port as well as a huge number of other new features and bug fixes. While this is still officially a development release because some API details are still not frozen, we believe that 2.9.2 can be used in production environment, especially for the new projects for which (small) changes in behaviour since 2.8 are not a problem.
- Source: http://wxwidgets.org
wxWidget appears very hard and difficult for the beginner. But when you get into it, it becomes gradually simple and interesting for you. It is a purely C++ library and is totally object oriented.