Function add

docs/welcome/lib/executr/lib/CodeMirror/codemirror.js:720–725

(left, top, width, bottom)

    var clientWidth = display.lineSpace.offsetWidth, pl = paddingLeft(cm.display);

    function add(left, top, width, bottom) {
      if (top < 0) top = 0;
      fragment.appendChild(elt("div", null, "CodeMirror-selected", "position: absolute; left: " + left +
                               "px; top: " + top + "px; width: " + (width == null ? clientWidth - left : width) +
                               "px; height: " + (bottom - top) + "px"));
    }

    function drawForLine(line, fromArg, toArg, retTop) {
      var lineObj = getLine(doc, line);