I haven't had any problems with PNG's with transparancy created in photoshop and loaded in BlitzMax --- everything showed up correctly.
(Easy to test for yourself as well: Just create a small image with nothing but a black-to-transparent gradient fill, and save as PNG. Make sure to set blend mode to AlphaBlend in BlitzMax)
(Easy to test for yourself as well: Just create a small image with nothing but a black-to-transparent gradient fill, and save as PNG. Make sure to set blend mode to AlphaBlend in BlitzMax)