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.cc
if (devtools_web_contents_.IsEmpty())
    return v8::Null(isolate);
  else
    return v8::Local<v8::Value>::New(isolate, devtools_web_contents_);
}
v8::Local<v8::Value> WebContents::Debugger(v8::Isolate* isolate) {
  if (debugger_.IsEmpty()) {
    auto handle = atom::api::Debugger::Create(isolate, web_contents());
    debugger_.Reset(isolate, handle.ToV8());
  }
  return v8::Local<v8::Value>::New(isolate, debugger_);
}
void WebContents::BuildPrototype(v8::Isolate* isolate,
                                 v8::Local<v8::ObjectTemplate> prototype) {
  mate::ObjectTemplateBuilder(isolate, prototype)
      .MakeDestroyable()
      .SetMethod("getId", &WebContents::GetID)
      .SetMethod("equal", &WebContents::Equal)
      .SetMethod("_loadURL", &WebContents::LoadURL)
      .SetMethod("downloadURL", &WebContents::DownloadURL)
      .SetMethod("_getURL", &WebContents::GetURL)
      .SetMethod("getTitle", &WebContents::GetTitle)
      .SetMethod("isLoading", &WebContents::IsLoading)
      .SetMethod("isLoadingMainFrame", &WebContents::IsLoadingMainFrame)
      .SetMethod("isWaitingForResponse", &WebContents::IsWaitingForResponse)
      .SetMethod("_stop", &WebContents::Stop)
      .SetMethod("_goBack", &WebContents::GoBack)
      .SetMethod("_goForward", &WebContents::GoForward)