[K12OSN] X system keyboard settings vs. GNOME keyboard settings

[Petre Scheie]

I'm using IceWM with my 4.2.1 server.  Whenever a user logs in at a 
client, after IceWM comes up, an 'Information' dialog box pops up that says

"The Xsystem keyboard settings differ from your current GNOME keyboard 
settings.  Which set would you like to use?"

and there are two choices, 'Use X Settings' and 'Use GNOME Settings'.  
What does this mean?  Why does it come up?  Which one should users be 
choosing?

Petre