* Output of `node_modules/.bin/electron --version`: 2.0.0
* Operating System (Platform and Version): Windows 10

**Expected Behavior**
When I disable a window twice via `setEnabled(false)`, I expect the second disable to have no effect.

**Actual behavior**
The second disable is "queued" up, such that I am forced to enable the window twice to get back to normal.

**To Reproduce**
In the electronquickstart repo, in main.js' `createWindow()`, add these lines:

    mainWindow.setEnabled(false);
    mainWindow.setEnabled(false);
    mainWindow.setEnabled(true);

The window will be disabled when launched. 

You see the same issue if you do it in reverse:

    mainWindow.setEnabled(true);
    mainWindow.setEnabled(false); // this doesn't actually disable it, because the window was enabled from the getgo

If this is expected behavior, can the [docs](https://github.com/electron/electron/blob/master/docs/api/browser-window.md#winsetenabledenable) be updated to explain this behavior.
atom/browser/native_window_views.h
base::win::ScopedHICON window_icon_;
  base::win::ScopedHICON app_icon_;
  
  static std::set<NativeWindowViews*> forwarding_windows_;
  static HHOOK mouse_hook_;
  bool forwarding_mouse_messages_ = false;
  HWND legacy_window_ = NULL;
  bool layered_ = false;
#endif
  
  std::unique_ptr<views::UnhandledKeyboardEventHandler> keyboard_event_handler_;
  
  
  std::unique_ptr<SkRegion> draggable_region_;  
  
  int disable_count_ = 0;
  bool use_content_size_ = false;
  bool movable_ = true;
  bool resizable_ = true;
  bool maximizable_ = true;
  bool minimizable_ = true;
  bool fullscreenable_ = true;
  std::string title_;
  gfx::Size widget_size_;
  double opacity_ = 1.0;
  DISALLOW_COPY_AND_ASSIGN(NativeWindowViews);
};
}  
#endif