mutiple-inheritance

What are real-world examples of C++ multiple inheritance?

Besides textbook examples -- in the real world -- does it ever make sense to use multiple inheritance (where more than one of the base classes are not pure interfaces) in C++? ...

Refactoring a leaf class to a base class, and keeping it also a interface implementation

I am trying to refactor a working code. The code basically derives an interface class into a working implementation, and I want to use this implementation outside the original project as a standalone class. However, I do not want to create a fork, and I want the original project to be able to take out their implementation, and use mine....