Comment 5 for bug 244766

IMHO: Whenever a guide has a color set (and not the default is used) the color should stay as such. Then changing the background is the workaround to see the guides again. If the guide colors is not changed and default, they could have a dynamic behavior. In this way, people can also choose to have complete control over the guides color (and use different colors) or they have a dynamic color (when no color is set) when needed in respect to the background.