Background selector didn't work

[sudgy]

I decided to look at the different backgrounds.  At first it was working fine, but after a few different ones it wasn't always working (it would just stay on the current background), then after a while it stopped working altogether.  I could still switch to no background but then was stuck on it.  However, upon refreshing it worked fine.  I know it doesn't help that I can't reproduce it but here you go.

I have Debian Linux 8.6, and my browser is Chromium version 53.0.2785.143.