* Electron version: 1.6.5
* Operating system: macOS Sierra

If you have a window with native tab bar to the top and you open a new window, it will open as separate window. But if you are in fullscreen mode, that new window will be attached as tab. Would it make sense to have API to force a window to open into an existing tab group or not? This would make it possible to give the user the choice of wether a window should open as tab or not independent from being in fullscreen mode or not.

Not even sure such API exists on macOS though.

/cc @tonyganch
atom/browser/native_window.h
void NotifyWindowLeaveFullScreen();
  void NotifyWindowEnterHtmlFullScreen();
  void NotifyWindowLeaveHtmlFullScreen();
  void NotifyWindowExecuteWindowsCommand(const std::string& command);
  void NotifyTouchBarItemInteraction(const std::string& item_id,
                                     const base::DictionaryValue& details);
  void NotifyNewWindowForTab();
  #if defined(OS_WIN)
  void NotifyWindowMessage(UINT message, WPARAM w_param, LPARAM l_param);
  #endif
  void AddObserver(NativeWindowObserver* obs) {
    observers_.AddObserver(obs);
  }
  void RemoveObserver(NativeWindowObserver* obs) {
    observers_.RemoveObserver(obs);
  }
  brightray::InspectableWebContents* inspectable_web_contents() const {
    return inspectable_web_contents_;
  }
  bool has_frame() const { return has_frame_; }
  void set_has_frame(bool has_frame) { has_frame_ = has_frame; }
  bool transparent() const { return transparent_; }
  SkRegion* draggable_region() const { return draggable_region_.get(); }
  bool enable_larger_than_screen() const { return enable_larger_than_screen_; }
  NativeWindow* parent() const { return parent_; }
  bool is_modal() const { return is_modal_; }
 protected:
  NativeWindow(brightray::InspectableWebContents* inspectable_web_contents,
               const mate::Dictionary& options,
               NativeWindow* parent);