now nottify gui stop update.
As far as I know, QT is a framework. When you are using a framework you have to build your application around the framework.
But Nifty-gui is a library, and a library do not impose that restriction. You can plug and play different gui-libraries if needed with minor/no modification to the rest of your program. Some members in the forum have rolled out their own gui library.
And a game engine(i.e. jME) needs a library, not a framework.