Multihead in GTK 2.2

["Jeremy Wilkins" <jeb jeremywilkins freeserve co uk>]

This is probably a dum question, but I haven't been able to find any info on
it.

How do I tell gtk what the second display is for multihead support, should
there be another env variable (eg $DISPLAY)? Will this work if the displays
are separate X servers?

Thanks

Jeb