These icons has following copy rights:
close.png : Used by jquery --> GPL
yast-* : GPL
yui : jquery tree widget --> GPL
webyast-logo.png : GPL
yast.config.png : GPL
monitoring.png : Tango icon --> GPL
edit-icon.png  : Tango icon --> GPL
delete.png : Tango icon --> GPL
loupe-icon.png : crystal_project
working.gif : generated with www.ajaxload.info/ --> free
go-*2.png: Tango icon --> GPL

Images which contains gradient stuff only (no copyright neede
for this kind of files):

button-gradient.png
cat-gradient.png
fill-gradient.png
input-bg.png
input-gradient.png
line.png
search-gradient.png