I use the following in my ~/.lispworks file. It’s not comprehensive but it’s better than nothing. I found the basic code in a google search… the only thing I could find… made a few slight modifications and used the colors I wanted. I also turn off “Color parenthesis” in the preferences because black is one of the colors used.
; dark theme
(defun set-pane-background-colors (x)
(typecase x
(capi:echo-area-pane
(setf (capi:simple-pane-background x) :black
(capi::simple-pane-foreground x) :orange))
(capi:collector-pane
(setf (capi:simple-pane-background x) :black
(capi::simple-pane-foreground x) :orange))
(capi:listener-pane
(setf (capi:simple-pane-background x) :black
(capi::simple-pane-foreground x) :orange))
(capi:editor-pane
(setf (capi::simple-pane-background x) :black
(capi::simple-pane-foreground x) :orange))
(capi:output-pane
(setf (capi:simple-pane-background x) :black
(capi::simple-pane-foreground x) :orange))
(capi:tab-layout
(mapcar 'set-pane-background-colors (capi:tab-layout-panes x)))))
(let ((*HANDLE-WARN-ON-REDEFINITION* :warn)
(*redefinition-action* :warn))
(defmethod capi:interface-display :before ((self lw-tools:listener))
(capi:map-pane-descendant-children
self 'set-pane-background-colors))
(defmethod capi:interface-display :before ((self lw-tools:editor))
(capi:map-pane-descendant-children
self 'set-pane-background-colors)))