Transparent stickers on transparent bricks with opaque print

[Jaco van der Molen]

Hi all,

I was wondering how to make transparent stickers on transparent bricks with opaque print.
Like the windows on the side in set 40252. 



Reading this thread I don't quite follow
https://forums.ldraw.org/thread-22204.html

I thought I'd just make a png image with transparent background and the azure blue triangular shape.
But applying that and make the brick transparent makes the pattern transparent too.

Can I achieve an opaque pattern?