You need a C++ framework, such as the Windows API or Java API, or a cross-platform GUI library. There is no way to create a GUI with just core C++. It is not designed for that.
There is no way to create a GUI with just core C++.
If you make past all layers of abstractions modern OS place between user programs and hardware, you can interact directly with device and draw what you want. Or just install older OS (e.g. DOS) in VM and play with it there.
To already suggested frameworks I would like to add FLTK: It is lightweight and cross-platform. It is even has own WYSIWYG editor called FLUID.
It is possible to use multimedia/game libraries such as SFML or SDL to build a GUI, but note that these libraries don't come with GUI classes and functions ready to use so you would have to build the GUI pretty much from scratch, or use additional libraries.
If you make past all layers of abstractions modern OS place between user programs and hardware, you can interact directly with device and draw what you want. Or just install older OS (e.g. DOS) in VM and play with it there.
You are correct, I failed to clarify my statement by mentioning writing a UI is no easy task.