Change iframe background with theme selection

[theAdhocracy]

Is there a way to change the background colour of the iframe/body element when a different them is selected? Currently we're using the addon-backgrounds plugin as well which gives us some capability, but the workflow of changing theme, then changing background isn't that streamlined.

It would be great if selecting the theme actively applied a background colour instead. I've tried emulating this using wrappers but to no success. Open to ideas on whether this is (or could be) possible.

[r0zar]

I came here to enter this feature request, it's pretty critical for when some themes are dark and some are light focused.

[rickyzhangca]

I too was trying to use another decorator to achieve this, didn't have luck