Assorted links
https://stackoverflow.com/questions/41631011/my-qt-eventfilter-doesnt-stop-events-as-it-should https://stackoverflow.com/questions/28746541/qt-mousemove-event-not-being-caught-in-eventfilter https://gist.github.com/Legor/a00760b6d7af32c01357fb7ff76ad86a
Covariant return types You can declare an abstract class and then override the return type in the derived class This is useful for when multiple classes implement a function but want to return an instance of themselves https://isocpp.org/wiki/faq/virtual-functions#virtual-ctors See Serializable.h and any entity class