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 Undo();
  void Redo();
  void Cut();
  void Copy();
  void Paste();
  void PasteAndMatchStyle();
  void Delete();
  void SelectAll();
  void Unselect();
  void Replace(const base::string16& word);
  void ReplaceMisspelling(const base::string16& word);
  uint32_t FindInPage(mate::Arguments* args);
  void StopFindInPage(content::StopFindAction action);
  void ShowDefinitionForSelection();
  
  void Focus();
  void TabTraverse(bool reverse);
  
  bool SendIPCMessage(bool all_frames,
                      const base::string16& channel,
                      const base::ListValue& args);
  
  void SendInputEvent(v8::Isolate* isolate, v8::Local<v8::Value> input_event);
  
  void BeginFrameSubscription(mate::Arguments* args);
  void EndFrameSubscription();
  
  void SetSize(const SetSizeParams& params);
  bool IsGuest() const;