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* Electron version: 2.0.0-beta.3
* Operating system: Ubuntu 16.04.04 LTS

### Expected behavior

App menu should be visible

### Actual behavior

App menu is invisible

### How to reproduce

- Run `electron`
- Observe that the app menu is invisible. It is still possible to open submenus.

![screenshot from 2018-03-14 17-01-18](https://user-images.githubusercontent.com/19880051/37415303-7296c25e-27ab-11e8-8284-d213c8bf5230.png)

atom/browser/native_window_views.cc
wm::SetShadowElevation(
      GetNativeWindow(),
      has_shadow ? wm::ShadowElevation::MEDIUM : wm::ShadowElevation::NONE);
}
bool NativeWindowViews::HasShadow() {
  return GetNativeWindow()->GetProperty(wm::kShadowElevationKey)
      != wm::ShadowElevation::NONE;
}
void NativeWindowViews::SetOpacity(const double opacity) {
#if defined(OS_WIN)
  HWND hwnd = GetAcceleratedWidget();
  if (!layered_) {
    LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
    ex_style |= WS_EX_LAYERED;
    ::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
    layered_ = true;
  }
  ::SetLayeredWindowAttributes(hwnd, 0, opacity * 255, LWA_ALPHA);
#endif
  opacity_ = opacity;
}
double NativeWindowViews::GetOpacity() {