- Electron version: v0.36.9
- Operating system: Windows 10/OS X

In #779 a `disposition` was added to the `new-window` event in [webContents](https://github.com/atom/electron/blob/master/docs/api/web-contents.md#event-new-window) but it always seems to be set to `new-window` when clicking on target="_blank" links in our web app wrapper: https://github.com/irccloud/irccloud-desktop/blob/v0.1.3/app/main.js#L109

If I Ctrl (Win) or Cmd (OS X) or middle click on links, I would expect to see a `background-tab` disposition, as in Chrome that will open links in a background tab, while keeping focus on the current tab. I'd like to catch this behaviour to set `activate` to false in `shell.openExternal`.

Is this possible?

atom/browser/api/atom_api_web_contents.cc
const base::ListValue& args) {
  return Send(new AtomViewMsg_Message(routing_id(), channel, args));
}
void WebContents::SendInputEvent(v8::Isolate* isolate,
                                 v8::Local<v8::Value> input_event) {
  const auto view = web_contents()->GetRenderWidgetHostView();
  if (!view)
    return;
  const auto host = view->GetRenderWidgetHost();
  if (!host)
    return;
  int type = mate::GetWebInputEventType(isolate, input_event);
  if (blink::WebInputEvent::isMouseEventType(type)) {
    blink::WebMouseEvent mouse_event;
    if (mate::ConvertFromV8(isolate, input_event, &mouse_event)) {
      host->ForwardMouseEvent(mouse_event);
      return;
    }
  } else if (blink::WebInputEvent::isKeyboardEventType(type)) {
    content::NativeWebKeyboardEvent keyboard_event;
    if (mate::ConvertFromV8(isolate, input_event, &keyboard_event)) {
      host->ForwardKeyboardEvent(keyboard_event);
      return;
    }
  } else if (type == blink::WebInputEvent::MouseWheel) {
    blink::WebMouseWheelEvent mouse_wheel_event;
    if (mate::ConvertFromV8(isolate, input_event, &mouse_wheel_event)) {
      host->ForwardWheelEvent(mouse_wheel_event);
      return;
    }