It is not worth currently to spend much time on this so I fixed it as fast as possible by syncing the default colors instead of creating a single source of truth. This code location was barely touched in the past decade and I don't see why this would receive suddenly much more attention than that.

Regarding the delayed update of the Image Navigator I decided to leave it as is as it is as minor as it can be but would require major code changes. My first idea was to react on OnPreferencedChanged() in the view but this is only triggered for preferences associated with the view, not the preferences of the standard multi widget.