- 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
content::WebContents* web_contents,
    const GURL& security_origin,
    content::MediaStreamType type) {
  return true;
}
void WebContents::RequestMediaAccessPermission(
    content::WebContents* web_contents,
    const content::MediaStreamRequest& request,
    const content::MediaResponseCallback& callback) {
  auto permission_helper =
      WebContentsPermissionHelper::FromWebContents(web_contents);
  permission_helper->RequestMediaAccessPermission(request, callback);
}
void WebContents::RequestToLockMouse(
    content::WebContents* web_contents,
    bool user_gesture,
    bool last_unlocked_by_target) {
  auto permission_helper =
      WebContentsPermissionHelper::FromWebContents(web_contents);
  permission_helper->RequestPointerLockPermission(user_gesture);
}
void WebContents::BeforeUnloadFired(const base::TimeTicks& proceed_time) {