- Electron version:1.3.3
- Operating system:win10/mac

the Tray instance events shold provide the tray hover event. 
`tray.setToolTip` has limitations when do more operation.

atom/browser/api/atom_api_tray.cc
v8::Local<v8::FunctionTemplate> prototype) {
  prototype->SetClassName(mate::StringToV8(isolate, "Tray"));
  mate::ObjectTemplateBuilder(isolate, prototype->PrototypeTemplate())
      .MakeDestroyable()
      .SetMethod("setImage", &Tray::SetImage)
      .SetMethod("setPressedImage", &Tray::SetPressedImage)
      .SetMethod("setToolTip", &Tray::SetToolTip)
      .SetMethod("setTitle", &Tray::SetTitle)
      .SetMethod("setHighlightMode", &Tray::SetHighlightMode)
      .SetMethod("displayBalloon", &Tray::DisplayBalloon)
      .SetMethod("popUpContextMenu", &Tray::PopUpContextMenu)
      .SetMethod("setContextMenu", &Tray::SetContextMenu)
      .SetMethod("getBounds", &Tray::GetBounds);
}
}  
}  
namespace {
using atom::api::Tray;
void Initialize(v8::Local<v8::Object> exports, v8::Local<v8::Value> unused,
                v8::Local<v8::Context> context, void* priv) {
  v8::Isolate* isolate = context->GetIsolate();
  Tray::SetConstructor(isolate, base::Bind(&Tray::New));
  mate::Dictionary dict(isolate, exports);
  dict.Set("Tray", Tray::GetConstructor(isolate)->GetFunction());
}
}  
NODE_MODULE_CONTEXT_AWARE_BUILTIN(atom_browser_tray, Initialize)