SP5: Warning message before deleting content in staging mode only

Staging content is not versioned in Jahia. There is no "undo" command. So deleting such content is a final no return action.

It would be great to have some kind of warnings when you delete some content which is in staging mode only (never validated or whose modifications are not published yet) and to mention that some content objects will be definitvely lost and could not be restored.