Function maybeScrollWindow

static/editor.md/lib/codemirror/lib/codemirror.js:4404–4419

(cm, coords)

  // If an editor sits on the top or bottom of the window, partially
  // scrolled out of view, this ensures that the cursor is visible.
  function maybeScrollWindow(cm, coords) {
    if (signalDOMEvent(cm, "scrollCursorIntoView")) return;

    var display = cm.display, box = display.sizer.getBoundingClientRect(), doScroll = null;
    if (coords.top + box.top < 0) doScroll = true;
    else if (coords.bottom + box.top > (window.innerHeight || document.documentElement.clientHeight)) doScroll = false;
    if (doScroll != null && !phantom) {
      var scrollNode = elt("div", "\u200b", null, "position: absolute; top: " +
                           (coords.top - display.viewOffset - paddingTop(cm.display)) + "px; height: " +
                           (coords.bottom - coords.top + scrollGap(cm) + display.barHeight) + "px; left: " +
                           coords.left + "px; width: 2px;");
      cm.display.lineSpace.appendChild(scrollNode);
      scrollNode.scrollIntoView(doScroll);
      cm.display.lineSpace.removeChild(scrollNode);
    }
  }

  // Scroll a given position into view (immediately), verifying that
  // it actually became visible (as line heights are accurately