- 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::RenderFrameHost* render_frame_host) {
  if (!render_frame_host->GetParent())
    Emit("dom-ready");
}
void WebContents::DidFinishLoad(content::RenderFrameHost* render_frame_host,
                                const GURL& validated_url) {
  bool is_main_frame = !render_frame_host->GetParent();
  Emit("did-frame-finish-load", is_main_frame);
  if (is_main_frame)
    Emit("did-finish-load");
}
void WebContents::DidFailProvisionalLoad(
    content::RenderFrameHost* render_frame_host,
    const GURL& url,
    int error_code,
    const base::string16& error_description,
    bool was_ignored_by_handler) {
  Emit("did-fail-provisional-load", error_code, error_description, url);
}
void WebContents::DidFailLoad(content::RenderFrameHost* render_frame_host,
                              const GURL& validated_url,
                              int error_code,
                              const base::string16& error_description,
                              bool was_ignored_by_handler) {
  Emit("did-fail-load", error_code, error_description, validated_url);
}
void WebContents::DidStartLoading() {