title: How to disable download in plone4.3
body: <p>In plone 4.3 i have write some code in plone4.3 at_download.when people access a url contain "at_download" they will be blocked. But when click the url didn't contain the "at_download" they also can download the file.</p>
  
  <p>thanks.</p>
  
  <p>I use documentviewer to display .doc .pdf .ppt,i just want allow them to view the file with document viewer.but can't download file from url.</p>