One of my previous employers maintains a blog that is mainly about Qt and UX design, with a sprinkling of more general C++ and software design subjects; I published three blogs there:
An Introduction to Clang Part 2
I also created the Qt Signal Adapter template library. It allows one to connect Qt signals to regular C++ function objects. Probably mostly obsolete, as newer versions of Qt provide the same functionality with several overloads of the connect method. There is learning value in the library, as it shows how to use the Qt meta object system to create slots and signals on the fly and invoke them dynamically.