Warning
gtk_icon_factory_lookup has been deprecated since version 3.10 and should not be used in newly-written code. Use GtkIconTheme instead.
Looks up stock_id in the icon factory, returning an icon set
if found, otherwise NULL. For display to the user, you should
use gtk_style_lookup_icon_set() on the GtkStyle for the
widget that will display the icon, instead of using this
function directly, so that themes are taken into account.
Warning gtk_icon_factory_lookup has been deprecated since version 3.10 and should not be used in newly-written code. Use GtkIconTheme instead. Looks up stock_id in the icon factory, returning an icon set if found, otherwise NULL. For display to the user, you should use gtk_style_lookup_icon_set() on the GtkStyle for the widget that will display the icon, instead of using this function directly, so that themes are taken into account.