* 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 defined(OS_WIN)
  DWORD affinity = enable ? WDA_MONITOR : WDA_NONE;
  ::SetWindowDisplayAffinity(GetAcceleratedWidget(), affinity);
#endif
}
void NativeWindowViews::SetFocusable(bool focusable) {
#if defined(OS_WIN)
  LONG ex_style = ::GetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE);
  if (focusable)
    ex_style &= ~WS_EX_NOACTIVATE;
  else
    ex_style |= WS_EX_NOACTIVATE;
  ::SetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE, ex_style);
  SetSkipTaskbar(!focusable);
  Focus(false);
#endif
}
void NativeWindowViews::SetMenu(AtomMenuModel* menu_model) {