Quote: Originally Posted by Romulinx2
You can put the themes/theme groups in any location, then click on the group and it will be installed. Think thats what you asked?
no sorry - not exactly:
available backgrounds are grouped by several tags like "Textures", "Vistas", "Light Auras" etc.
Some searching led me to the conclusion that Windows 7 is using the information stored in the metadata-field "Markierungen" (german) which should translate into something like "tag". If you open the folder directly from explorer (C:\Windows\Web\Wallpaper) and select "group by" + "Markierungen", you'll get exactly the same list which is displayed in the wallpaper selector.
So the only remaining question is how to change the data in that field. "Properties" of the file shows it on the Details-Tab, but doesn't allow changes.