- Electron version: v0.37.5
- Operating system: Any

It would be useful if we can open DevTools choosing all of it's available position: detached, docked right or docked bottom.

The new API could be something like this:
# webContents.openDevTools([options])

Opens the devtools.
- options Object (optional)
  - mode String - ['detached' | 'right' | 'bottom'] . opens DevTools in specified position. Defaults to last used mode.
  - detach Boolean - opens DevTools in a new window (deprecated, use mode: 'detached')

atom/browser/api/atom_api_web_contents.cc
const std::string& frame_name,
                                 WindowOpenDisposition disposition) {
  if (type_ == BROWSER_WINDOW)
    Emit("-new-window", target_url, frame_name, disposition);
  else
    Emit("new-window", target_url, frame_name, disposition);
}
content::WebContents* WebContents::OpenURLFromTab(
    content::WebContents* source,
    const content::OpenURLParams& params) {
  if (params.disposition != CURRENT_TAB) {
    if (type_ == BROWSER_WINDOW)
      Emit("-new-window", params.url, "", params.disposition);
    else
      Emit("new-window", params.url, "", params.disposition);
    return nullptr;
  }
  
  if (Emit("will-navigate", params.url))
    return nullptr;
  return CommonWebContentsDelegate::OpenURLFromTab(source, params);
}
void WebContents::BeforeUnloadFired(content::WebContents* tab,