title: How to remove git ignored files from GitX Staged area
body: <p>I removed some files from git index , using <code>git rm --cached</code>.</p>
  
  <p>Those files were already staged before.<br>
  Now those files still shows at the GitX stage area, with red icon near them.<br>
  I would like them disappear, that's the reason I ignored them.</p>
  
  <p>I tried <code>git update-index --assume-unchanged</code> to no avail.</p>
  
  <p>Any advice ?</p>