* 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.cc
#if defined(OS_WIN)
  Microsoft::WRL::ComPtr<ITaskbarList> taskbar;
  if (FAILED(::CoCreateInstance(CLSID_TaskbarList, nullptr,
                                CLSCTX_INPROC_SERVER,
                                IID_PPV_ARGS(&taskbar))) ||
      FAILED(taskbar->HrInit()))
    return;
  if (skip) {
    taskbar->DeleteTab(GetAcceleratedWidget());
  } else {
    taskbar->AddTab(GetAcceleratedWidget());
    taskbar_host_.RestoreThumbarButtons(GetAcceleratedWidget());
  }
#elif defined(USE_X11)
  SetWMSpecState(GetAcceleratedWidget(), skip,
                 GetAtom("_NET_WM_STATE_SKIP_TASKBAR"));
#endif
}
void NativeWindowViews::SetSimpleFullScreen(bool simple_fullscreen) {