* 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
return widget()->GetNativeView();
}
gfx::NativeWindow NativeWindowViews::GetNativeWindow() const {
  return widget()->GetNativeWindow();
}
void NativeWindowViews::SetProgressBar(double progress,
                                       NativeWindow::ProgressState state) {
#if defined(OS_WIN)
  taskbar_host_.SetProgressBar(GetAcceleratedWidget(), progress, state);
#elif defined(USE_X11)
  if (unity::IsRunning()) {
    unity::SetProgressFraction(progress);
  }
#endif
}
void NativeWindowViews::SetOverlayIcon(const gfx::Image& overlay,
                                       const std::string& description) {
#if defined(OS_WIN)
  taskbar_host_.SetOverlayIcon(GetAcceleratedWidget(), overlay, description);
#endif
}
void NativeWindowViews::SetAutoHideMenuBar(bool auto_hide) {