added the #:draw-border? argument to disk and filled-ellipse

collects/scribblings/slideshow/picts.scrbl

@@ -233,10 +233,14 @@ override settings supplied by the context.}
 
 @defproc*[([(ellipse [w real?] [h real?]) pict?]
            [(circle [diameter real?]) pict?]
-           [(filled-ellipse [w real?] [h real?]) pict?]
+           [(filled-ellipse [w real?] [h real?] [#:draw-border? draw-border? any/c #t]) pict?]
-           [(disk [diameter real?]) pict?])]{
+           [(disk [diameter real?] [#:draw-border? draw-border? any/c #t]) pict?])]{
 
-Unfilled and filled ellipses.}
+Unfilled and filled ellipses.
+
+If @racket[draw-border?] is @racket[#f], then the pen is set to be transparent
+before drawing the ellipse.
+}
 
 @defproc*[([(rectangle [w real?] [h real?]) pict?]
            [(filled-rectangle [w real?]

collects/texpict/utils.rkt

@@ -344,16 +344,21 @@
 	    (send dc set-brush b)))
 	width height))
 
-  (define (disk size) (filled-ellipse size size))
+  (define (disk size #:draw-border? [draw-border? #t])
+    (filled-ellipse size size #:draw-border? draw-border?))
   
-  (define (filled-ellipse width height)
+  (define (filled-ellipse width height #:draw-border? [draw-border? #t])
     (dc (lambda (dc x y)
-	  (let ([b (send dc get-brush)])
+	  (define b (send dc get-brush))
+          (define p (send dc get-pen))
           (send dc set-brush (send the-brush-list find-or-create-brush
                                    (send (send dc get-pen) get-color)
                                    'solid))
+          (unless draw-border?
+            (send dc set-pen "black" 1 'transparent))
           (send dc draw-ellipse x y width height)
-	    (send dc set-brush b)))
+          (send dc set-brush b)
+          (send dc set-pen p))
 	width height))
 
   (define cloud