Widget background blur

In my inventory system I want make the background more blurry, so it is easier to see the actual slots and items. I know this effect is possible in ue4 4.15 but my level is in 4.14 and I don’t want to update this particular level. Is it possible to recreate this effect without having to update the level? The effect is noticeable in Rust for example:

assuming your background there is from the camera and not just a static image you should be able to do it with a post process effect. I’m not certain, but I think there was a blur effect the content examples project.

How would I do that?