I think I've seen the post you're referring too and have implemented it already in the post above. I'm calling graphics with GRAPHICS_ALPHABUFFER flag and using a different cls function to set the alpha to 0 when it clears the screen.
If you save the pixmap as a png file and look at it in a paint program it certainly has alpha, just seems like it's too much.
If you save the pixmap as a png file and look at it in a paint program it certainly has alpha, just seems like it's too much.