I've discovered that the latest (1.18.3.5) Mac SL viewer mis-renders the depth (x-position) of certain HUD objects, whereas the Windows and Linux clients render the same HUD objects properly. The viewer confuses the depth of some (but not all) alpha-mapped prims in the HUD, no matter what relative depth is between the prims. Relinking the HUD doesn't seem to help either.
Has anybody else encountered this problem?
Update: Guess I'm not the first person to notice: this big is known as VWR-579 on Jira
https://jira.secondlife.com/browse/VWR-579