> btw. do you have any idea if the GX supports some sort of
> colour-keying?  Like defining a transparent colour for
> screen-to-screen blits?

As far as I know it does not.  You can use an arbitrary rasterop based
on the foreground colour, the background colour, the source colour, and
the destination colour, but only bitwise - that is,
"result-bit = arbitrary-boolean-function(fg-bit,bg-bit,src-bit,dst-bit)"
(all 65536 possible functions are available as far as I can tell).  And
you can use the planemask register to, effectively, write-protect some
bitplanes.  But if what you want can't be expressed that way, I don't
know any way for the cg6 to do it.  For example the "transparent
colour" notion, in which a destination bit cannot in general be
computed without looking at all the source bits for that pixel (not
just the bit corresponding to the destination bit in question) is not
available - or at least if it is I have no idea how to get it.

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