The best way to start a File-Drag for now, is the downloadURL as i know.

Like here in Nylas N1:
https://github.com/nylas/N1/blob/master/internal_packages/attachments/lib/attachment-component.cjsx#L67

But only Images and PDFs are able to Drop direct on an Application (MAC). Other file formats just can be copied to Folders.
I think I'm not the only one who is looking for a full native file drop and I think chromium offers that already.

On chrome://downloads/ its possible to Drag any File on an Application (Mac).

Is there maybe a way to access this Drag Function in electron or can it become a part of?
Multi File Drag would be very nice too! :)

[chrome://downloads/ > js dragstart > chrome.send('drag', id)](https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/resources/md_downloads/crisper.js&q=crisper.js&sq=package:chromium&type=cs&l=15751)

I have no knowledge, about cc++ but it found that... :D
[drag_download_item_views.cc](https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/download/drag_download_item_views.cc&q=DragDownloadItem&sq=package:chromium&dr=CSs&l=31)
[md_downloads_dom_handler.cc](https://chromium.googlesource.com/chromium/src.git/+/master/chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.cc)

atom/browser/api/atom_api_web_contents.h
void RequestMediaAccessPermission(
      content::WebContents* web_contents,
      const content::MediaStreamRequest& request,
      const content::MediaResponseCallback& callback) override;
  void RequestToLockMouse(
      content::WebContents* web_contents,
      bool user_gesture,
      bool last_unlocked_by_target) override;
  std::unique_ptr<content::BluetoothChooser> RunBluetoothChooser(
      content::RenderFrameHost* frame,
      const content::BluetoothChooser::EventHandler& handler) override;
  
  void BeforeUnloadFired(const base::TimeTicks& proceed_time) override;
  void RenderViewDeleted(content::RenderViewHost*) override;
  void RenderProcessGone(base::TerminationStatus status) override;
  void DocumentLoadedInFrame(
      content::RenderFrameHost* render_frame_host) override;
  void DidFinishLoad(content::RenderFrameHost* render_frame_host,
                     const GURL& validated_url) override;
  void DidFailLoad(content::RenderFrameHost* render_frame_host,
                   const GURL& validated_url,
                   int error_code,
                   const base::string16& error_description,
                   bool was_ignored_by_handler) override;
  void DidFailProvisionalLoad(content::RenderFrameHost* render_frame_host,
                              const GURL& validated_url,
                              int error_code,
                              const base::string16& error_description,
                              bool was_ignored_by_handler) override;
  void DidStartLoading() override;