Matthias Clasen <mclasen(a)redhat.com> writes:
Supported formats for themed icons are xpm, png and svg. Thus, if
you
install the icon below /usr/share/icons/hicolor/ it should be in one of
those formats. If you install it in /usr/share/pixmaps, it can really be
anything, but traditionally, that directory is for xpms. In the desktop
file, the icon should be either specified as a full path (including
extension) or as an icon name (without extension), the latter being
preferred.
I guess the appropriate question for this list is "where is all that
documented?"
regards, tom lane