Well done. There are many paths to the goal...

Hi TIG and MtnTrails, Thank's for your advices! The hint on changing the size of the colour thumbnails made me find out how to do: Firstly; chose medium size thumbnails, secondly; let the window get as small width as possible (it cant be smaller than a certain width). Now, all colours suddenly has a logic arrangement. Any other thumbnail size or window width make the colours show up in appearantly random order.