Undefined variable $DRAW_USE_PNGCAIRO



On my system I get a warning about an undefined variable
$DRAW_USE_PNGCAIRO when loading the draw package.

Maxima version: 5.23post
Maxima build date: 11:42 1/8/2011
Host type: i686-pc-linux-gnu
Lisp implementation type: SBCL
Lisp implementation version: 1.0.45


(%i1) load(draw);

;     (AND (EQ MAXIMA::VAL 'MAXIMA::$PNG) MAXIMA::$DRAW_USE_PNGCAIRO)
; --> IF AND 
; ==>
;   (THE T MAXIMA::$DRAW_USE_PNGCAIRO)
; 
; caught WARNING:
;   undefined variable: $DRAW_USE_PNGCAIRO
; 
; compilation unit finished
;   Undefined variable:
;     $DRAW_USE_PNGCAIRO
;   caught 1 WARNING condition
(%o1)        /usr/local/share/maxima/5.23post/share/draw/draw.lisp

Dieter Kaiser