HDRP: Is it possible yet to get full-screen UI blur? (2019.1 + HDRP 5.13)

I've tried to tackle this before, and I always end up having to back off because something isn't ready. I'm checking again whether it's yet possible to get a full-screen blur under the latest HDRP.

The two main issues preventing me from doing this are:

• It doesn't seem that any Master output nodes available to ShaderGraph can be used on Screen Space UI elements. If I try to create a shader in ShaderGraph and use it on an image in a Screen Space canvas, it's just blank.
• It doesn't seem like I can access Screen Color in a legacy Shaderlab shader.

As a workaround, I've tried putting the blur effect on a World Space canvas, but there are various reasons why this isn't really viable. (The worst being getting the placement exact so that nothing is in front of the blur plane.

So, under HDRP 5.13, is it possible to create a ShaderGraph shader that can be use in a screen space canvas? Or is it possible to access Screen Color in a legacy shader? Any other options for full-screen blur, without resorting to world-space canvases?

 

I think what we really need in this case are command buffer CameraEvents for "AfterUI" and "BeforeUI" for the purposes of extending post processing that includes UI.

 

Second this.

 

Wish the devs would notice this