* Electron version: 1.4.14
* Operating system: Windows 8.1

### Expected behavior

A fullscreen transparent window should be transparent.

### Actual behavior

The window is not transparent (has a white background).

### How to reproduce

```
electron.app.on("ready", function () {
    var win = new BrowserWindow({
        show: true,
        frame: false,
        fullscreen: true,
        transparent: true
    });
});
```

Refs https://github.com/electron/electron/issues/8321#issuecomment-273615701


atom/browser/native_window_views.cc
if (is_modal() && NativeWindow::parent())
    static_cast<NativeWindowViews*>(NativeWindow::parent())->SetEnabled(false);
  window_->native_widget_private()->ShowWithWindowState(GetRestoredState());
  NotifyWindowShow();
#if defined(USE_X11)
  if (global_menu_bar_)
    global_menu_bar_->OnWindowMapped();
#endif
}
void NativeWindowViews::ShowInactive() {
  window_->ShowInactive();
  NotifyWindowShow();
#if defined(USE_X11)
  if (global_menu_bar_)
    global_menu_bar_->OnWindowMapped();
#endif
}
void NativeWindowViews::Hide() {
  if (is_modal() && NativeWindow::parent())
    static_cast<NativeWindowViews*>(NativeWindow::parent())->SetEnabled(true);
  window_->Hide();
  NotifyWindowHide();
#if defined(USE_X11)
  if (global_menu_bar_)
    global_menu_bar_->OnWindowUnmapped();
#endif
}
bool NativeWindowViews::IsVisible() {