Gets the filename for the icon. If the GTK_ICON_LOOKUP_USE_BUILTIN
flag was passed to IconTheme.lookupIcon, there may be no
filename if a builtin icon is returned; in this case, you should
use IconInfo.getBuiltinPixbuf.
the filename for the icon, or NULL
if IconInfo.getBuiltinPixbuf should be used instead.
The return value is owned by GTK+ and should not be modified
or freed.
Gets the filename for the icon. If the GTK_ICON_LOOKUP_USE_BUILTIN flag was passed to IconTheme.lookupIcon, there may be no filename if a builtin icon is returned; in this case, you should use IconInfo.getBuiltinPixbuf.