In SqueakMap, there are two packages that should allow you to do this. 
Those two packages have to be loaded in this order:
    AppearanceMenuRegistry
    Edit Text Colors for Squeak 3.4 ((20-apr-2003))

I loaded both both items into the plain 3.8 image and successfully 
changed the colors without any issues.

hope this helps,
Larry Trutter

Andreas Raab wrote:

> Hi -
>
> How do I change the rules for syntax highlighting in 3.8 full? I 
> really don't like the way this looks. Is there a user interface for it?
>
> Thanks,
>   - Andreas
>
>