- Electron version: 1.2.0, 1.2.1, 1.2.2
- Operating system: Windows

If you start an browser window in fullscreen and then attempt to toggle to windowed mode, the window will just black out and become unresponsive. Attempting to toggle back again still results in a black screen.

However, if you start the window in windowed mode and then toggle to fullscreen, it works as expected.

This maybe related to the fixes made to the fullscreen API in 1.2.x. It only occurs on Windows. It does not happen on 1.1.3.

You can reproduce easily with the `electron-api-demos` application and 1.2.2.
https://github.com/electron/electron-api-demos

Update `window-options` to set `fullscreen: true`
https://github.com/electron/electron-api-demos/blob/master/main.js#L22

```
var windowOptions = {
      width: 1080,
      minWidth: 680,
      height: 840,
      title: app.getName(),
      fullscreen: true
    }
```

Start the application and hit F11 to switch to windowed mode and you'll get a black screen.

atom/browser/native_window_views.cc
#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) {
#if defined(OS_WIN)
  HMENU menu = GetSystemMenu(GetAcceleratedWidget(), false);
  if (closable) {
    EnableMenuItem(menu, SC_CLOSE, MF_BYCOMMAND | MF_ENABLED);
  } else {
    EnableMenuItem(menu, SC_CLOSE, MF_BYCOMMAND | MF_DISABLED | MF_GRAYED);
  }
#endif
}
bool NativeWindowViews::IsClosable() {