I'm not sure if this has been reported SR SPR, but when applying emissive material to a decal, the mapping gets screwed up. These are png images and it happens with planar mapping. I'm simulating an lighted LCD screen.

decal applied and properly scaled and positioned:

and then emissive material applied:

No matter what you do to try and scale the decal, reposition it etc. you can not fit it properly to the face that it is being applied to. It looks like once emissive is applied as an appearance to the decal, that it behaves like a tiled texture...?