Comment 6 for bug 927110

just to show you the current status.
In attached image, the changes to minimap.
On winterland only, if the ownership layer is not shown, the color of building/flags/roads switch to orange, otherwise these elements are not visible.

Of course color can be changed, if you suggest a better one.

same logic can be applied to other worlds, also, but at the moment I think it's not needed.