LispWorks (version 5.0 and greater) is a "themed" application on Microsoft Windows XP and later versions. Themes alter the appearance of some CLIM panes.
To make CLIM appear as on earlier versions of Windows and in LispWorks 4.x, call
before creating any CLIM windows.
Common Lisp Interface Manager 2.0 User's Guide - 7 Aug 2017