Cycling 74 has not yet finished evaluating Mac OS 10.5, aka Leopard.
As with any new OS, you are advised to tread cautiously if you are
considering updating. We are interested in hearing any and all reports
from users, and at some later date we shall publish full details of
our compatibility. Until that time use of our software on Leopard is unsupported.
If you wish to make reports of your experience with Leopard, please send them to support at cycling74 dot com