[Cairo] Cairo on older X servers, (eg. with Render version 0.2)

[Keith Packard]

Around 11 o'clock on Sep 30, Carl Worth wrote:

> If Cairo can assume that nothing external to Cairo will be drawing to any
> drawable that has been handed to Cairo, then a lot of useless image
> transfer can be eliminated with a couple of lines of code.

I think we have to make this assumption or cairo will be worthless without
Render -- that includes all non-X environments.  The only trick I see is 
in having cairo track the size of the drawable; I don't have any great 
ideas here as the library can't do this on it's own, and it will only 
matter when you don't have Render, leaving the system prone to failure in 
those cases.

It might also be nice to have some kind of 'flush' operation which ensures 
that the target drawable contains the rendering results.

-keith