- 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
v8::Local<v8::Value> val,
                     atom::SetSizeParams* out) {
    mate::Dictionary params;
    if (!ConvertFromV8(isolate, val, &params))
      return false;
    bool autosize;
    if (params.Get("enableAutoSize", &autosize))
      out->enable_auto_size.reset(new bool(true));
    gfx::Size size;
    if (params.Get("min", &size))
      out->min_size.reset(new gfx::Size(size));
    if (params.Get("max", &size))
      out->max_size.reset(new gfx::Size(size));
    if (params.Get("normal", &size))
      out->normal_size.reset(new gfx::Size(size));
    return true;
  }
};
template<>
struct Converter<PrintSettings> {
  static bool FromV8(v8::Isolate* isolate, v8::Local<v8::Value> val,