PyQt slot called when the user hits the "Clear" button.
        Removes any set custom module search path.

def on_clear_button_pressed(self):
        """
        PyQt slot called when the user hits the "Clear" button.
        Removes any set custom module search path.
        """
        self.path = None
        self.clear_button.setEnabled(False)
        self.folder_label.setText(self.initial_folder_label_text)
        logger.debug("User selects to clear the custom module search path.")