[HIG] Window Border Icons

[Dave Bordoley <bordoley msu edu>]

Another action item for calum :)

Now that we have reasonably good icon theming in gnome, I think that the
hig should specify that window border icons (they are also used in the
window list) for apps that view and edit documents should use the icon
for the mime type of the currently viewed file. 

In addition if a thumbnail exists for the file (i believe thumbnailing
is also supported in the standard libs now), than the thumbnail should
be use for the window border icon/window list.

dave