LW + OS X, layout issues

Dear list,

I am trying to layout a push-button and a popup field (option-pane)
with a row-layout. Both panes have the same y position specified but
then option-pane is placed 2 pixel rows above. Why is this the case ?

Is it possible to use the pinboard-layout (or even row-layout) with a guarantee
that all controls are layouted properly on the same y position ?

Here's a code snippet:


(define-interface opengl-interface ()
  ()
  (:panes (opengl opengl-pane
                  :configuration (list :rgba t :double-buffered t)
                  :display-callback 'gl-display
                  :resize-callback  'gl-resize
                  :min-width 256
                  :min-height 256

          (popup capi:option-pane
                  :visible-min-width 200
                  :x 320
                  :y 5
                 :items (loop for i below 20 collect i)
                 :visible-items-count 6)

          (button capi:push-button
                  :visible-min-width 100
                  :x 5
                  :y 5
                  :text "OK"
                  :callback 'go-button-blicked
                  :callback-type :interface))

  (:layouts
   (controls-layout capi:pinboard-layout
                    '(button popup))

   (main column-layout '(controls-layout opengl) :default t))

  (:default-initargs :window-styles '(:internal-borderless
                                      :textured-background)))


Best regards,
Walantis