Drag and Drop Files as Attachement when creating an Incident

I'd like to have drag and drop for attachements
So I have read this https://community.cireson.com/discussion/101/copy-paste-or-drag-and-drop-attachments-via-cireson-portals and tried it.
But on the new incident form it is still not possible to add this attachements with drag and drop.
How can I achieve this?