* 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)
  return ::GetWindowLong(GetAcceleratedWidget(), GWL_STYLE) & WS_MINIMIZEBOX;
#else
  return true;  
#endif
}
void NativeWindowViews::SetMaximizable(bool maximizable) {
#if defined(OS_WIN)
  FlipWindowStyle(GetAcceleratedWidget(), maximizable, WS_MAXIMIZEBOX);
#endif
  maximizable_ = maximizable;
}
bool NativeWindowViews::IsMaximizable() {
#if defined(OS_WIN)
  return ::GetWindowLong(GetAcceleratedWidget(), GWL_STYLE) & WS_MAXIMIZEBOX;
#else
  return true;  
#endif
}
void NativeWindowViews::SetFullScreenable(bool fullscreenable) {
  fullscreenable_ = fullscreenable;
}
bool NativeWindowViews::IsFullScreenable() {
  return fullscreenable_;
}
void NativeWindowViews::SetClosable(bool closable) {