Function extend

static/editor.md/lib/codemirror/lib/codemirror.js:3638–3656

(e)

    var counter = 0;

    function extend(e) {
      var curCount = ++counter;
      var cur = posFromMouse(cm, e, true, type == "rect");
      if (!cur) return;
      if (cmp(cur, lastPos) != 0) {
        ensureFocus(cm);
        extendTo(cur);
        var visible = visibleLines(display, doc);
        if (cur.line >= visible.to || cur.line < visible.from)
          setTimeout(operation(cm, function(){if (counter == curCount) extend(e);}), 150);
      } else {
        var outside = e.clientY < editorSize.top ? -20 : e.clientY > editorSize.bottom ? 20 : 0;
        if (outside) setTimeout(operation(cm, function() {
          if (counter != curCount) return;
          display.scroller.scrollTop += outside;
          extend(e);
        }), 50);
      }
    }

    function done(e) {
      counter = Infinity;