- Electron version: `0.37.4`
- Operating system: Windows

When I maximize my [frameless](https://github.com/electron/electron/blob/master/docs/api/frameless-window.md) electron window a small part of the window in an unmaximized state is visible on a secondary monitor.

**Screenshot**
![electronbug](https://cloud.githubusercontent.com/assets/6634592/14762341/8849c728-09bb-11e6-85d8-de12db3fee2d.PNG)

You can visibly see the "line between the monitors" and you can see some really strange overhanging content that is over that line.

**Steps to reproduce**  
1. Open an electron app
2. Maximize the app on your secondary display
3. Look closely for the overflow onto your primary display

This might take a few times to trigger, it appears to do it about 70% of the time :confused: 

atom/browser/native_window_views.cc
return window_->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,