- 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_app.cc
.SetMethod("addRecentDocument",
                 base::Bind(&Browser::AddRecentDocument, browser))
      .SetMethod("clearRecentDocuments",
                 base::Bind(&Browser::ClearRecentDocuments, browser))
      .SetMethod("setAppUserModelId",
                 base::Bind(&Browser::SetAppUserModelID, browser))
      .SetMethod("setAsDefaultProtocolClient",
                 base::Bind(&Browser::SetAsDefaultProtocolClient, browser))
      .SetMethod("removeAsDefaultProtocolClient",
                 base::Bind(&Browser::RemoveAsDefaultProtocolClient, browser))
#if defined(OS_MACOSX)
      .SetMethod("hide", base::Bind(&Browser::Hide, browser))
      .SetMethod("show", base::Bind(&Browser::Show, browser))
      .SetMethod("isDarkMode",
                 base::Bind(&Browser::IsDarkMode, browser))
#endif
#if defined(OS_WIN)
      .SetMethod("setUserTasks",
                 base::Bind(&Browser::SetUserTasks, browser))
      .SetMethod("isAeroGlassEnabled", &App::IsAeroGlassEnabled)
#endif
      .SetMethod("setPath", &App::SetPath)
      .SetMethod("getPath", &App::GetPath)
      .SetMethod("setDesktopName", &App::SetDesktopName)
      .SetMethod("allowNTLMCredentialsForAllDomains",
                 &App::AllowNTLMCredentialsForAllDomains)
      .SetMethod("getLocale", &App::GetLocale)
      .SetMethod("makeSingleInstance", &App::MakeSingleInstance);
}
mate::Handle<App> App::Create(v8::Isolate* isolate) {