Windows and X widgets (wxWidgets) is an open source, cross-platform widget toolkit; that is, a library of basic elements for building a graphical user interface (GUI)
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. Unlike other cross-platform toolkits, wxWidgets applications look and feel native. This is because wxWidgets uses the platform's own native controls rather than emulating them. It's also extensive, free, open-source, and mature.
With this tutorial you will learn how to use the wxWidgets toolkit to create elegant and highly useful GUIs in your programming language of choice.
But why use wxWidgets? Because you want to be able to write a GUI quickly and easily that runs across platforms. You also want to be able to use the programming language of your choice, and you want your GUI looks cool or same on all platform.
Personally, I prefer to use QT toolkit. But I will give a shot to wxWidgets :D