Mask from 2D UI widgets for a Post Process Material

What method(s) can I use to access, or render, a mask of all - or some - 2D UI widgets?
(A mask that is accessible in a Post Process material).

I’m trying to apply a post-processing effect in my scene, but I only want the effect where my 2D UI widgets are (and they are movable and re-sizable by the user, so I can’t rely on a static mask).

I’ve tried using a SceneTexture:SeparateTransluceny node in my post process material, without any luck (and there’s a message saying “Not yet supported” when it’s selected in the dropdown list of the SceneTexture node, which probably explains why nothing happens).

Hi ,

There is a feature request that I’ve updated to include you functionality. Unreal Engine Issues and Bug Tracker (UE-16058)

Since there aren’t very many votes the community interest seems low. I would recommend going there and voting on the feature request so that this can be viewed as more important to the community.