Comment 42 for bug 162993

We have to have a solution so that the same release build will display stock icons when libgnomeui is present and will display some other icons when libgnomeui is not present (e.g. for KDE users). So a build-time only solution is a short-term hack but I think the real solution really does block Firefox 3 so we'd better work on that now anyway.

I think we have to ship the winstripe icons as part of gnomestripe and find some way of making the stock icon CSS rules conditional on libgnomeui being present. One way that I think would actually be quite nice is to create a new nsILookAndFeel value to signal whether stock icons are available and use the :-moz-system-metric CSS pseudo-class in theme stylesheets to select the icon. In gtk2/nsLookAndFeel.cpp we would check whether stock icons are available. We'd add an atom here ("stock-icon-available")?
http://mxr.mozilla.org/seamonkey/source/layout/style/nsCSSRuleProcessor.cpp#749
by querying the new nsILookAndFeel value.