Edit a table. Click 'Properties' and set it to 'sortable'. See no change on the table. Wonder whether it worked. Check the properties tab again. Yes, it's set. Wonder what's going on.
Edit a table. Click 'Properties' and set it to 'sortable'. See something change on the page (add the correct set of arrows to the top row? Pop up an annoying little message to say that it worked?). Be confident that it worked.