title: How to use font awesome in an Ext.panel.Tool
body: <p>I need to customize an Ext.panel.Tool to display the icon 'fa fa-file-excel-o' from font awesome in the header of a grid. Following what I found online I have declared the tool:</p>
  
  <pre><code>    header: {
      itemPosition: 1, // after title before collapse tool
      items: [{
          xtype: 'tool',
          type: 'export',
          cls:'component-tool-export',
          handler: 'doExportData'
      }]
      },
  </code></pre>
  
  <p>And the css:</p>
  
  <pre><code>.component-tool-export .x-tool-export{
    background-image:none !important;
    content: "\f1c3" !important;
  }
  </code></pre>
  
  <p>The tool is there and I can click on it, but the icon is not displayed. Can anyone give me some hint to fix this?</p>