LispWorks uses GTK+ as the default window system for CAPI and the LispWorks IDE on Linux, FreeBSD, AIX and x86/x64 Solaris. GTK+ is also supported on Mac OS X as an alternative to Cocoa. LispWorks requires GTK+ 2 (version 2.4 or higher).
Note: LispWorks on SPARC Solaris does not support GTK+.
A few known problems are documented on Problems with CAPI on GTK+.
LispWorks 7.1 requires Imlib2 1.4.3 or later to use the Motif GUI on Linux, FreeBSD, Mac OS X and AIX. Previous versions of LispWorks required Imlib, which is a different library and is still required on Solaris.
LispWorks Release Notes and Installation Guide - 19 Oct 2017