Make preview a bit bigger.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@14403 20353a03-c40f-0410-a6d1-a30d3c3de9de

bt5/erp5_dms/SkinTemplateItem/portal_skins/erp5_dms/Drawing_viewAsWeb/drawing_preview.xml

@@ -261,7 +261,7 @@
                 </item>
                 <item>
                     <key> <string>image_display</string> </key>
-                    <value> <string>thumbnail</string> </value>
+                    <value> <string>medium</string> </value>
                 </item>
                 <item>
                     <key> <string>image_format</string> </key>