title: how to prevent text selection when dragging mouse in Firefox?
body: <p>I am wondering how those drag and drop widgets cancel text selection in the dragging element and other elements in the page. I tried the following code which works in IE8 (cannot select text) but does not work (can still select text) in Firefox.</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;body&gt;
    &lt;p&gt;Hello World&lt;/p&gt;
    &lt;script type="text/javascript"&gt;
      document.onmousemove = function() {
        return false;
    }
    &lt;/script&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>