public/javascript/libs/wysihtml5-0.3.0.js
function() {
      var win       = this.doc.defaultView,
          selection = win.getSelection();
      selection.modify("extend", "left", "lineboundary");
      selection.modify("extend", "right", "lineboundary");
    }
function() {
      var win       = this.doc.defaultView,
          selection = win.getSelection();
      selection.modify("extend", "left", "lineboundary");
      selection.modify("extend", "right", "lineboundary");
    }
See https://developer.mozilla.org/en/DOM/Selection/modify