The C++ standard library is extremely light. It contains nowhere near the functionality offered by the Java runtimes or by the .NET CLR.
The Boost libraries add a whole bunch of functionality to C++, but not much (if any) in the area of user interface.
For UI, there's the question of which platform you're targetting. If it's Win32, then you can use the straight Win32 API (mostly designed for C, but there are some C++ wrappers for parts of it). If you want cross-platform, then you're looking at QT or GTK (although there are others).
But, as Andrew already said: "why do you want to learn C++ anyway?". Don't get me wrong: I program in C++ for a living, and actually enjoy it (although I'm beginning to suspect a case of Stockholm Syndrome). If I had to start again, I'd go with a more modern language and environment (Java or C#; or Ruby or Python).