The LispWorks editor currently relies on integral font sizes. Some Mac OS X fonts have non-integral size and will be displayed incorrectly in the Editor and Listener tools and other uses of
capi:editor-pane
.
The solution is to use a font with integral size. The following are known to work: Monaco 10, Monaco 15, Monaco 20.
Select the font in an Editor or Listener tool by Window > Window Preferences... > Font .