Toggle AutoCAD Background

This bit of lisp code will toggle the background color from white to black to white in whatever space you are in. (no effect on the block editor though...)

(vl-load-com)
(defun c:TBC (/ pref col tm)
  (setq tm (getvar "tilemode"))
  (setq pref (vla-get-display
        (vla-get-Preferences
                  (vlax-get-acad-object)
               )
      )
  )
  (if (zerop tm)
    (setq cur (vla-get-graphicswinlayoutbackgrndcolor pref))
    (setq cur (vla-get-graphicswinmodelbackgrndcolor pref))
  )
  (setq col (vlax-variant-value
       (vlax-variant-change-type
         cur
         vlax-vblong
       )
     )
  )
  (if (not (or (eq col 0) (eq col 16777215)))
    (setq col 0)
  )
  (cond ((zerop tm)
  (vla-put-graphicswinlayoutbackgrndcolor
      pref
      (vlax-make-variant (abs (- col 16777215)) vlax-vblong)
  )
  (vla-put-layoutcrosshaircolor
      pref
      (vlax-make-variant col vlax-vblong)
  )
 )
 (t
  (vla-put-graphicswinmodelbackgrndcolor
      pref
      (vlax-make-variant (abs (- col 16777215)) vlax-vblong)
  )
  (vla-put-modelcrosshaircolor
      pref
      (vlax-make-variant col vlax-vblong)
  )
 )
  )
  (vlax-release-object pref)
  (princ)
)