Wanted to check in about a problem we've been having rendering transparency in Motion. The issue is that objects with any kind of opacity gradient to them -- shapes with glow, fog and flame emitter particles, and so on -- lose much of their visibility when the project background is set to transparent and the render is subsequently brought into FCP7.
Here's a quick test. The lightning bolt shape with a glow on it overlaps both a blue shape and the background.
Here's a frame grab from FCP where the background was set to "solid" in Motion:
Note how the glow falls off where the blue shape ends. This dropoff is particularly obvious when the object is in motion, creating a moving hard edge. Objects with low opacity to begin with, such as fog and flames, almost disappear entirely.
This issue also occurs in the version of Pixelmator I'm running, 1.6.5 -- which is a couple versions back at this point. Notably this issue does not occur in FCPX. Currently the workaround is to composite in FCPX and bring that back into FCP7. But if there's a direct fix for the FCP7 issue, that would be swell.