I am not sure if it is beneficial to change inheritance to QWidget for all plugins. For example with comboBoxes we will just create similar API for Signals/Slots anyway at the end. I think it is good to have signals such as currentIndexChanded(int) or currentTextChanged(QString)
@appel_c I would say that we can close this, I would keep smaller widgets (the ones which are only one widget) to inherit from the appropriate Qt class rather than generic QWidget.