- 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
return web_contents()->IsWaitingForResponse();
}
void WebContents::Stop() {
  web_contents()->Stop();
}
void WebContents::GoBack() {
  atom::AtomBrowserClient::SuppressRendererProcessRestartForOnce();
  web_contents()->GetController().GoBack();
}
void WebContents::GoForward() {
  atom::AtomBrowserClient::SuppressRendererProcessRestartForOnce();
  web_contents()->GetController().GoForward();
}
void WebContents::GoToOffset(int offset) {
  atom::AtomBrowserClient::SuppressRendererProcessRestartForOnce();
  web_contents()->GetController().GoToOffset(offset);
}
bool WebContents::IsCrashed() const {
  return web_contents()->IsCrashed();
}
void WebContents::SetUserAgent(const std::string& user_agent) {
  web_contents()->SetUserAgentOverride(user_agent);
  scoped_refptr<net::URLRequestContextGetter> getter =
      web_contents()->GetBrowserContext()->GetRequestContext();
  auto accept_lang = l10n_util::GetApplicationLocale("");
  getter->GetNetworkTaskRunner()->PostTask(FROM_HERE,
      base::Bind(&SetUserAgentInIO, getter, accept_lang, user_agent));
}
std::string WebContents::GetUserAgent() {