Loads given DataFile object. **tolerant with None**

        Args:
            fobj: object of one of accepted classes
            index: tab index to load fobj into. If not passed, loads into current tab

def load(self, fobj, index=None):
        """
        Loads given DataFile object. **tolerant with None**

        Args:
            fobj: object of one of accepted classes
            index: tab index to load fobj into. If not passed, loads into current tab
        """
        if index is None:
            index = self._get_tab_index()
        page = self.pages[index]

        if fobj is None:
            return


        if not isinstance(fobj, tuple(page.clss_load)):
            raise RuntimeError('Object to load must be in {0!s} (not a {1!s})'.format(
             [x.__name__ for x in page.clss_load], fobj.__class__.__name__))

        page.editor.load(fobj)
        self._update_gui_text_tabs()