What is this supposed to do? Why does it inherit from QQuickWindow? How can a window be a shared engine? The name is probably badly chosen.

The API contains both view/window related functions (size stuff etc.) as well as engine related functions (translation domain). The latter should probably be removed and the shared engine available internally made publically accessible, such that the engine-related functions can be called on it directly?

Also, inheriting from QQuickWindow - is that really required, or could composition be used instead to reduce the coupling? Think of user code that's already creating a QQuickWindow elsewhere and would like to use whatever this class is offering.