themes Allow Themes to Have a Gradient Background

[Ahti333]

While investigating input delay after upgrading to High Sierra (setting blur below 50% fixed it, as mentioned here fixed it for now), I found this weird behaviour:

 

When setting the blur to about here:

 

my Alfred window suddenly had a gradient background:

 

While this is a bit much, I'd love to be able to have a gradient background in my theme, which could look amazing I think.

[Ahti333]

Oh, I forgot, these are my system specs in case you need them for reproducing this or sth: