Created attachment 35793 [details] [review]
slist_handle.diff

So, you solved the first problem. Here is a further patch, but the ints are
garbage. Maybe you could look in case you see something obvious.

Created attachment 35798 [details] [review]
dodgy_ints.patch

I was looking at the gconf internals and they use GPOINTER_TO_INT to convert a
GSList* of ints/bools to a Value list for storing (look at
gconf_value_list_from_primitive_list at
http://cvs.gnome.org/viewcvs/gconf/gconf/gconf-internals.c?rev=1.130&view=auto).
 I think the easiest way to do that would be to reverse that and call
GINT_TO_POINTER on our ints/bools.  I'm still not sure how to handle the doubles.

Well done. That works for ints and bools. Now we just need to figure out the
floats - there is commented-out test code in the client example.

If you look in gconf_value_list_to_primitive_list_destructive of that same file
I posted here earlier, they allocate some space for a gdouble.  We should
probably do it that way.

Here's the code:
[snip]
          case GCONF_VALUE_FLOAT:
            {
              gdouble* d = g_new(gdouble, 1);
              *d = gconf_value_get_float(elem);
              tmp->data = d;
            }
            break;
[snip]

The default BasicTypesTraits now does this, and it works.