--- a/web/views/basetemplates.py	Mon Jul 22 14:57:37 2013 +0200
+++ b/web/views/basetemplates.py	Mon Jul 22 15:38:11 2013 +0200
@@ -162,6 +162,7 @@
         self.write_doctype()
         # explictly close the <base> tag to avoid IE 6 bugs while browsing DOM
         self._cw.html_headers.define_var('BASE_URL', self._cw.base_url())
+        self._cw.html_headers.define_var('DATA_URL', self._cw.datadir_url)
         w(u'<meta http-equiv="content-type" content="%s; charset=%s"/>\n'
           % (content_type, self._cw.encoding))
         w(u'\n'.join(additional_headers) + u'\n')