fixup! erp5_interface_post: action to export all exportable Letter Post in only one PDF document

bt5/erp5_interface_post/SkinTemplateItem/portal_skins/erp5_interface_post/LetterPostModule_exportExportableLetterPostDialog.xml

@@ -6,6 +6,12 @@
     </pickle>
     <pickle>
       <dictionary>
+        <item>
+            <key> <string>_objects</string> </key>
+            <value>
+              <tuple/>
+            </value>
+        </item>
         <item>
             <key> <string>action</string> </key>
             <value> <string>LetterPostModule_exportExportableLetterPost</string> </value>
@@ -65,7 +71,10 @@
                 <item>
                     <key> <string>left</string> </key>
                     <value>
-                      <list/>
+                      <list>
+                        <string>my_description</string>
+                        <string>your_comment</string>
+                      </list>
                     </value>
                 </item>
                 <item>