Background color of pinboard layout

Hello,

On MAC : 

When using row-layout or column-layout the default background is
transparent.
But when using pinboard-layout the default background is white and I don't
find a solution to remove this undesirable solid color.

Here the layout is transparent :

(define-interface test-layout () ()
  (:panes (pane push-button-panel
            :items (loop for i from 0 to 3 collect
                      (make-instance 'push-button
                                     :text (string (nth i '(a b c d)))))))
  (:layouts (main row-layout '(pane))))

(display (make-instance 'test-layout))

After replacing row-layout by pinboard-layout, the layout becomes white and
the :background initarg set to :transparent doesn't solve the problem :
 
(define-interface test-layout () ()
  (:panes (pane push-button-panel
            :items (loop for i from 0 to 3 collect
                      (make-instance 'push-button
                                     :text (string (nth i '(a b c d)))))))
  (:layouts (main pinboard-layout '(pane) :x 15 :y 15
                 :background :transparent)))

Any suggestion ?


----------------------------------------------------
Denis Pousseur
34 Bd de Dixmude
1000 Bruxelles, Belgique
Mail :  denis.pousseur@compositeurs.be
Website : http://www.compositeurs.be
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