* 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
return ui::win::IsAeroGlassEnabled();
}
std::string hexColorDWORDToRGBA(DWORD color) {
  std::ostringstream stream;
  stream << std::hex << color;
  std::string hexColor = stream.str();
  return hexColor.substr(2) + hexColor.substr(0, 2);
}
std::string SystemPreferences::GetAccentColor() {
  DWORD color = 0;
  BOOL opaque = FALSE;
  if (FAILED(dwmGetColorizationColor(&color, &opaque))) {
    return "";
  }
  return hexColorDWORDToRGBA(color);
}
std::string SystemPreferences::GetColor(const std::string& color,
                                        mate::Arguments* args) {
  int id;
  if (color == "3d-dark-shadow") {
    id = COLOR_3DDKSHADOW;
  } else if (color == "3d-face") {
    id = COLOR_3DFACE;
  } else if (color == "3d-highlight") {
    id = COLOR_3DHIGHLIGHT;
  } else if (color == "3d-light") {