Using StandardGame?

- Configuring it!
Most gameType use propertiesIO class for configuration,
standardGame use GameSettings...
why?


The GameSettings system is much more powerful than the PropertiesIO.  I need to provide a simple means of displaying that information before load though the way that the PropertiesIO system works though.  In my games I provide those settings inside the game itself, which makes it easier to change your settings around at any time (see GameSettingsPanel).  You can simply create a JFrame that encapsulates the GameSettingsPanel that appears before the game starts and you'd have similar functionality though.

- how do we stop a GameState from being render?
(exemple : open the menu -> stop rendering the game)


Like Hal was trying to convey either gameState.setActive(false) or GameStateManager.getInstance().deactivateChildNamed("") or GameStateManager.getInstance().detachChild(gameState)

- I use JMEDesktop,
I tried to add it as a node like basicGame
But i failed, so i used the JMEDesktpState.


I would suggest using JMEDesktopState where it makes sense anyway.  If there is something you need beyond what JMEDesktopState provides though then take a look at it as an example of where to begin to create your own implementation.  Doing everything as a GameState is really beneficial as a powerful way of controlling your game.