Preload all data that for the tabs that will be displayed.

def load_tab_data(self):
        """Preload all data that for the tabs that will be displayed."""
        for tab in self._tabs.values():
            if tab.load and not tab.data_loaded:
                try:
                    tab._data = tab.get_context_data(self.request)
                except Exception:
                    tab._data = False
                    exceptions.handle(self.request)