sub-app fade

I want to fade the sub-app in and out when it appears and disappears. I've tried the Window Transparency object but it seems to be bugged for me (does transparency for the whole window instead of just the sub app, even when "use for sub-app" is checked) and the Sphax Kernel is for dev-only.

Is there any other way to do this?

Have you tried ticking "Display as sprite" in the properties? Then maybe you can fade something over it, remove it, and fade out the cover.

How do you use HWA effects with 'display as sprite'? I'm afraid I don't quite understand your solution.

Also I've heard 'display as sprite' doesn't work if you want to use it as a pause menu?

I don't recall mentioning HWA ;)

If you're using it as a pause screen then you're going to have to destroy it and have an image of what it looked like fade out instead.