title: jQuery draggable plugin i want to update px to mm on drag event
body: <p>i want to know if there is any trick or hack to j-query Drag-able plugin,
  so that <strong>on-drag</strong> event i want to update left and top position with unit <strong>mm</strong> not <strong>PX</strong> 
  for example</p>
  
  <pre><code>&lt;div id="text" style="position:relative;top:22px;left:100px;"&gt;sample text&lt;/div&gt;
  </code></pre>
  
  <p>should change to</p>
  
  <pre><code>&lt;div id="text" style="position:relative;top:22mm;left:100mm;"&gt;sample text&lt;/div&gt;
  </code></pre>
  
  <p>or how can i make a custom j-query plugin??to get this work</p>