Function add

static/editor.md/lib/codemirror/lib/codemirror.js:2244–2251

(left, top, width, bottom)

    var rightSide = Math.max(display.sizerWidth, displayWidth(cm) - display.sizer.offsetLeft) - padding.right;

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

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