Many thanks, IO4 - I'd never even noticed that little double-ended arrow before! I've only just upgraded from Bryce 3, but I just checked and it was there too!

And I thought I'd read the Bryce 3D manual from cover to cover (several times). Mind you, the pages are falling out of the manual....

Thanks again, nice to learn a new trick:-)

Cheers,
Diolma