nces-pane-spacer');

    this.$pane = document.createElement('div');
    this.$pane.setAttribute('id', 'references-pane');

    this.$container.appendChild($spacer);
    this.$container.appendChild(this.$pane);

    this.$header = document.createElement('div');
    this.$header.classList.add('menu-pane-header');
    this.$header.textContent = 'References to ';
    this.$headerRefId = document.createElement('a');
    this.$header.appendChild(this.$headerRefId);
    this.$closeButton = document.createElement(