I made a nice collection of lighthouse pictures as backgrounds, and saved it as a theme. I would like to have a dedicated window color for each picture, as for example in the United States Places Theme. Each picture there has a custom windows color for it, so the bottom panel is color-coordinated with the picture.

I tried choosing the color I wanted for each picture, saving it each time, but they didn't "take." They all just have the last color I had chosen.

Is there a way to do this, and have it persist?