Adding Attachment Using DnD Makes Document Unsaveable

I’m able to drag files into an open Wysiwyg editor, which will automatically upload the document as an attachment and create a link to it in the document.

However, the document cannot be saved anymore afterwards - which is especially annoying if the attachment wasn’t the only thing changed in the current editing session…

Also note that this error message box is not even visible of the Wysiwyg editor is running in fullscreen mode - the user clicks “save” and simply nothing happens, but (s)he also is not able to edit any more after clicking “save” and will not have any idea, why this is the case.

According to Vincent Massol in https://forum.xwiki.org/t/problem-when-adding-attachments-using-drag-and-drop-realtime/4523 this is a bug in RTWYSIWYG and should be filed here.