Ultimatte Knockout reports Mac OS 8.5.x "bug"

Ultimatte Knockout is a image masking application. On its web page is the following statement (thanks, Stan):

Mac OS 8.5.X Incompatibility: Ultimatte KnockOut Software is incompatible with Mac OS versions 8.5 and 8.5.1. There is a QuickDraw bug in OS 8.5.X that corrupts selection data. In many cases it simply displays the selection data incorrectly, but it may also corrupt the data and crash the computer. We are actively working on this problem with Apple and will distribute a free update once the problem is solved.

I was not aware of this bug. So I asked Apple's John Phelps for a reaction. He replied that he had not heard of it either. He did add: "Not sure what they mean by 'selection data', but since 8.5 converted a lot of system code to PowerPC, it's possible this application couldn't handle it."

Update: Joe Laffey writes: "I spoke to the tech support a few days ago and was told that Mac OS 8.6 fixes this "bug." They said it had to do with the migration of QuickDraw to PowerPC native code."