In my Galactic Commander game I change the default font doing something like this in a init() method of a BasicGameState:
defaultFont = new org.newdawn.slick.AngelCodeFont(...);
and at start of the main render() I do:
The results are quite strange. Most noticeably the text changes to whatever, where it is supposed to say one thing it says another because it was used earlier.
I've not been able to track this down in my code. There's no obvious reason why it behaves like this. Perhaps it's a bug in Slick how it handles a default font, maybe you're not allowed to change it?
I'll need to try to reproduce this perhaps. Will let you know of my results.