[pygame] The best LayeredDirty and DirtySprite tutorial?

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Subject: [pygame] The best LayeredDirty and DirtySprite tutorial?
From: René Dudfield <renesd@xxxxxxxxx>
Date: Thu, 14 Jul 2011 15:09:02 +0100
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Hey ya,

is there a really good tutorial existing which explains LayeredDirty and DirtySprite?

cheers,