Function onContextMenu

static/editor.md/lib/codemirror/lib/codemirror.js:4085–4088

(cm, e)

  // textarea (making it as unobtrusive as possible) to let the
  // right-click take effect on it.
  function onContextMenu(cm, e) {
    if (eventInWidget(cm.display, e) || contextMenuInGutter(cm, e)) return;
    cm.display.input.onContextMenu(e);
  }

  function contextMenuInGutter(cm, e) {
    if (!hasHandler(cm, "gutterContextMenu")) return false;