Eliminating scroll flicker with capi-internals:simple-pane-erase-background?

I have a pinboard (subclass) which needs to redraw while it's being scrolled (a zoomed-in view on a large amount of data, so I only draw to the viewport). I'm seeing a lot of flicker at the edges whilst scrolling, which I've only been able to eliminate by adding a method to capi-internals:simple-pane-erase-background for my subclass, as follows:

(defmethod capi-internals:simple-pane-erase-background
((self my-pinboard-layout))
nil)

Is there a more 'API-friendly' way I can do this, however? BTW I'm on XP.

Cheers,
Chris

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