CAPI: check-button-panel with scroll bar and white background

Hi,

I want to create a check-button-panel with a vertical scroll
bar, because there are too many check-buttons to fit on the screen.

So I do something like:

(capi:contain
 (make-instance 'capi:check-button-panel
                :title "Test"
                :items (loop for i below 100 collect (format nil "~R" i))
                :layout-class 'capi:column-layout
                :min-width 600 :visible-min-height 250
                :vertical-scroll t))

This works fine, except that I need a white background for the panel,
because that looks much better in the dialog box where I'm using this.
So I add a :background argument:

(capi:contain
 (make-instance 'capi:check-button-panel
                :title "Test"
                :items (loop for i below 100 collect (format nil "~R" i))
                :layout-class 'capi:column-layout
                :background :white
                :min-width 600 :visible-min-height 250
                :vertical-scroll t))

This seems to work too, except for one thing: I get garbage pixels
when I scroll through the items.  This does not happen with the
default (gray) background.

Is this a CAPI bug, or is there some other way to get a white background
in this case?

Thanks in advance,

Arthur Lemmens

(This is on LWW 4.3.7, Windows XP)