Drag and drop attachment from GMail?

I know that you can drag and drop attachments from GMail/Chrome into a local file system (like Windows Explorer or Ubuntu Nautilus). I have an upload object with a dropZone in my XML, which works perfectly if the file is already stored on the local file system. However, when I drag an attachment from GMail I can’t get it to drop in the drop zone.

Does anybody know what is required to make this work?