Image update strategy

[Cyrille Berger]

On Friday 04 April 2008, Sven Langkamp wrote:
> Isn't it very unlikely that an image contains a completely opaque layer?

When I draw I often a set of at least two (sometimes three) completely opaque 
layer. But I agree that I never have a transparent layer below it ;)

That said, the questions I ask my self: What's the benefit of this ? Should it 
be faster, and why ? Does this fix a bug, which one ?

-- 
Cyrille Berger