* Electron version: 1.4.4
* Operating system: win10

Hi,
Example described [here](https://github.com/electron/electron/blob/master/docs/api/global-shortcut.md) works with v1.4.0 but doesn't seem to work with v1.4.4 or v1.4.5.  Method `globalShortcut.isRegistered ` returns true, but the callback isn't called. 

Thanks!
atom/browser/api/atom_api_system_preferences_win.cc
#include "atom/browser/api/atom_api_system_preferences.h"
#include "atom/common/color_util.h"
#include "base/win/wrapped_window_proc.h"
#include "ui/base/win/shell.h"
#include "ui/gfx/color_utils.h"
#include "ui/gfx/win/hwnd_util.h"
namespace atom {
namespace {
const wchar_t kSystemPreferencesWindowClass[] =
  L"Electron_SystemPreferencesHostWindow";
}  
namespace api {
bool SystemPreferences::IsAeroGlassEnabled() {