docs: def center_widget_on_screen(widget, screen=None):
      """
      Centers given Widget on the screen.
  
      :param widget: Current Widget.
      :type widget: QWidget
      :param screen: Screen used for centering.
      :type screen: int
      :return: Definition success.
      :rtype: bool
      """
  
      screen = screen and screen or QApplication.desktop().primaryScreen()
      desktop_width = QApplication.desktop().screenGeometry(screen).width()
      desktop_height = QApplication.desktop().screenGeometry(screen).height()
      widget.move(desktop_width / 2 - widget.sizeHint().width() / 2, desktop_height / 2 - widget.sizeHint().height() / 2)
      return True