This change set provides a new editor allowing the easy modification of #colorPrint values. If you turn on the Browsing preferences of browseWithPrettyPrint colorWhenPrettyPrinting you can see these colors and attributes in action on code panes.
To open the editor perform: DialectStreamAttributesEditor open
With Squeak 3.5 this tool registers with the appearance registry and consequently appears in the appearance menu.