def handle_selected_page(self):
        """
        Open all selected pages in subwindows except other subreddit pages.
        """
        if not self.selected_page:
            pass
        elif self.selected_page.name in ('subscription', 'submission', 'inbox'):
            # Launch page in a subwindow
            self.selected_page = self.selected_page.loop()
        elif self.selected_page.name == 'subreddit':
            # Replace the current page
            self.active = False
        else:
            raise RuntimeError(self.selected_page.name)

        Open all selected pages in subwindows except other subreddit pages.
        
rtv/subreddit_page.py