Qt multithreading and let the second thread update the main (UI) thread

[jefftee]

Just as a clarification: only because this is a cross-thread signal/slot connection (Qt::QueuedConnection).
A direct connection does not require any thing from the argument types.

Thanks for clarifying. I will usually register my custom types whether or not I am using threads and cross-thread signals/slots. I believe the other beneficial reason to do so is that you can use QVariant for custom types that have been registered, which may come in handy too.