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
#include "atom/browser/native_window.h"
#include "atom/browser/net/atom_network_delegate.h"
#include "atom/browser/web_contents_permission_helper.h"
#include "atom/browser/web_contents_preferences.h"
#include "atom/browser/web_view_guest_delegate.h"
#include "atom/common/api/api_messages.h"
#include "atom/common/api/event_emitter_caller.h"
#include "atom/common/color_util.h"
#include "atom/common/mouse_util.h"
#include "atom/common/native_mate_converters/blink_converter.h"
#include "atom/common/native_mate_converters/callback.h"
#include "atom/common/native_mate_converters/content_converter.h"
#include "atom/common/native_mate_converters/file_path_converter.h"
#include "atom/common/native_mate_converters/gfx_converter.h"
#include "atom/common/native_mate_converters/gurl_converter.h"
#include "atom/common/native_mate_converters/image_converter.h"
#include "atom/common/native_mate_converters/string16_converter.h"
#include "atom/common/native_mate_converters/value_converter.h"
#include "atom/common/options_switches.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "brightray/browser/inspectable_web_contents.h"
#include "brightray/browser/inspectable_web_contents_view.h"
#include "chrome/browser/printing/print_view_manager_basic.h"
#include "chrome/browser/printing/print_preview_message_handler.h"
#include "content/browser/renderer_host/render_widget_host_impl.h"
#include "content/common/view_messages.h"
#include "content/public/browser/favicon_status.h"
#include "content/public/browser/native_web_keyboard_event.h"
#include "content/public/browser/navigation_details.h"