Bug when converting to new connect api. As reported by Albert and you can see phabricator review for this bug (in sddm) https://phabricator.kde.org/D19959 in sddm-kcm clazy converted: - connect(configUi->autoLogin, SIGNAL(clicked()), SIGNAL(changed())); + connect(configUi->autoLogin, &QGroupBox::clicked, this, &AdvanceConfig::changed); but signal AdvanceConfig::changed had a default value Q_SIGNALS: void changed(bool changed=true); and QGroupBox::clicked has default value == false => when we use new connect api it will emit: QGroupBox::clicked(value == false) => emit AdvanceConfig::changed(false) as we send value from clicked to changed => Prevously when we clicked on QGroupBox it emitted changed(true) as we didn't send "sender value" on reveiver. For me we mustn't change connect api when old api doesn't use argument and sender and receiver has a default argument. I don't know if we can detect it but it will