On X11/Motif the default fonts and colors (and certain other properties) used in CAPI elements are determined by the applicable X resources.
The file
app-defaults/Lispworks
, supplied in the LispWorks library for relevant platforms, contains the application fallback resources for LispWorks 5.1 and illustrates resources you may wish to change.
The file
app-defaults/GcMonitor
contains the application fallback resources for the Lisp Monitor window.
The files
app-defaults/*-classic
contain the fallback resources that were supplied with LispWorks 4.4.
For further information about X resources, consult documentation for the X Window system.