Signal initialization was improved by walking the MRO to find all signals. But this had the side effect that signals could be overwritten. This implementation resolves signals only once per name, so that only the most recent signal places an instance into the instance dict. Note: this does _not_ solve the equality problem of super().signal == super().signal # fails because the super call triggers a new signalInstance in the parent. This has to be addressed in a bigger rewrite if desired. [ChangeLog][PySide6] Signal initialization now respects the order of subclasses in the mro(). Change-Id: I7481576798ca272ebebf8e9a5ba875cfc94e8361 Fixes: PYSIDE-1751 Pick-to: 6.2 Task-number: PYSIDE-1431 Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>