Panel view mode doesn't work with custom fields

A very interesting feature in Display suite is working with custom fields. Particularly, the ability to add dynamics fields that have not been created with field ui module and are not viewable in "manage display" page. For instance, the sharethis module adds html code to a node by dynamically inserting a field like that:

This happens in a hook_node_view in sharethis module.

When using Display suite with "normal mode" i simply had to create a dynamic field in 'admin/structure/ds/fields/' page, name it "sharethis" for example, and, i was able to view it in the "manage diplay" page and give it a region.

Now i have activated the "Panel view mode" and use the panels editor, i can not see my dynamics fields. I mean, when i click on "Add content" in a region of my Panels editor, i can't find the field in whatever proposed categories (node, node(token), Miscellaneous etc ...).

My questions are the following: Is the feature willingly not supported by the Panel view mode ? Is it a bug ? Or, may it depend on the Panel module API and then i just created a discussion in the wrong group ?