I was talking about the system files (osclass version), not the theme files. I believe that some internal files may contain new updates that do not work in version 3.1.2. But i not yet check this situation. I just wanted to say if I would just update something in the content that relates to the method (drag and drop), just that and nothing any other update.
If somebody found where are this new functions and code for "drag and drop", please post.