What do I do if a slot is not invoked?

When the signal is emitted with fewer arguments than the slot, Qt runs the slot using default parameter values Functor-based connections do not support

Signals and slots are loosely coupled: A class which emits a signal neither knows nor cares which slots receive the signal Qt's signals and slots mechanism

qtech slot When a connection is configured, it becomes visible in Qt Designer's signal and slot editor where it can be further edited You can also edit signalslot

qt connect signal to slot Signals and slots are loosely coupled: A class which emits a signal neither knows nor cares which slots receive the signal Qt's signals and slots mechanism