When using wallpaper image for paper background, palettes' background instead uses most recently picked color

If you choose a color in Preferences > Canvas > Paper, that color becomes both the color of the paper in the score, and of the background of the palettes.

However, if instead of a color you choose to use a tiling wallpaper image, the palettes' background does not obey the setting, and instead uses whatever solid color was most recently selected.