qt wizard: WizardComponent: (fix) also inherit ABC

for `@abstractmethod` decorator to work
(except, turns out, it's not so simple because of pyqt's own magic for QWidget)

electrum/gui/qt/util.py

@@ -1,3 +1,4 @@
+from abc import ABC, ABCMeta
 import os.path
 import time
 import sys
@@ -1430,6 +1431,12 @@ def qt_event_listener(func):
     return decorator
 
 
+class _ABCQObjectMeta(type(QObject), ABCMeta): pass
+class _ABCQWidgetMeta(type(QWidget), ABCMeta): pass
+class AbstractQObject(QObject, ABC, metaclass=_ABCQObjectMeta): pass
+class AbstractQWidget(QWidget, ABC, metaclass=_ABCQWidgetMeta): pass
+
+
 if __name__ == "__main__":
     app = QApplication([])
     t = WaitingDialog(None, 'testing ...', lambda: [time.sleep(1)], lambda x: QMessageBox.information(None, 'done', "done"))

electrum/gui/qt/wizard/wizard.py

@@ -10,7 +10,7 @@ from PyQt5.QtWidgets import (QDialog, QPushButton, QWidget, QLabel, QVBoxLayout,
 
 from electrum.i18n import _
 from electrum.logging import get_logger
-from electrum.gui.qt.util import Buttons, icon_path, MessageBoxMixin, WWLabel, ResizableStackedWidget
+from electrum.gui.qt.util import Buttons, icon_path, MessageBoxMixin, WWLabel, ResizableStackedWidget, AbstractQWidget
 
 if TYPE_CHECKING:
     from electrum.simple_config import SimpleConfig
@@ -233,7 +233,7 @@ class QEAbstractWizard(QDialog, MessageBoxMixin):
         return True
 
 
-class WizardComponent(QWidget):
+class WizardComponent(AbstractQWidget):
     updated = pyqtSignal(object)
 
     def __init__(self, parent: QWidget, wizard: QEAbstractWizard, *, title: str = None, layout: QLayout = None):