I'm trying for instance to add a proper icon to a XLS file (excel). In fact in my system this kind of file is without the icon (the foot of the standard gnome application). Well, trying to set the icon with the file type menu I discover that none of the applications have a icon associated in that menu. In addition when I force the icon, this time the menu acknowledge the icon associate to excel speadsheet, but no effect on the icons displaied in Nautilus. Basically the visible icons, shown in Nautilus, are not in agreement to those shown in the file type association menu (wich have almost all empty icons). Hope to be clear, but ask if not. I'm wondering there has been some misalignment in the file that manage this function in Gnome.