I just booted on Mojave and used a in house application to resize images.
Works fine excepted there is a Windows XP developer who works in the image group at Apple: when I set the Alpha Channel to ON (*), instead of getting transparency, I get black (where I get transparency on El Capitan (and following).
Nota: the used application is a bit complex / I am a bit in a hurry: I do not know how I set the transparency (some images are initialized with the
,32 parameter, some dont; in
Not an impossible task and I already have to remanufacture that project to use a single window instead of 3 (one for each major OS).
And I seem to recall another bug somewhere (I hope I took notes for that bug).