code: function focusIssue() {
          return cs.start.node == cs.end.node && cs.start.offset == 0 && cs.end.offset == 0;
        }
docs: on webkit-based browsers, it is apparently possible that the selection gets reset even when a node that is not one of the endpoints get messed with. the most common situation where this occurs is when a selection is deleted or overwitten. we check for that here.