grafana/public/app/plugins/panel/text/editor.html

<div>
  <div class="row-fluid">
    <div class="span4">
      <label class="small">Mode</label> <select class="input-medium" ng-model="ctrl.panel.mode" ng-options="f for f in ['html','markdown','text']"></select>
    </div>
    <div class="span2" ng-show="ctrl.panel.mode == 'text'">
      <label class="small">Font Size</label> <select class="input-mini" ng-model="ctrl.panel.style['font-size']" ng-options="f for f in ['6pt','7pt','8pt','10pt','12pt','14pt','16pt','18pt','20pt','24pt','28pt','32pt','36pt','42pt','48pt','52pt','60pt','72pt']"></select>
    </div>
  </div>

  <label class=small>Content
    <span ng-show="ctrl.panel.mode == 'markdown'">(This area uses <a target="_blank" href="http://en.wikipedia.org/wiki/Markdown">Markdown</a>. HTML is not supported)</span>
  </label>

  <textarea ng-model="ctrl.panel.content" rows="20" style="width:95%" ng-change="ctrl.render()" ng-model-onblur>
  </textarea>
</div>