Test case:

---
#!/usr/bin/env python                                                                                                        

import gtk

t = gtk.ListStore (long)

for v in [ 18, 189015844108 ]:
    print type (v), v
    t.set (t.append (), 0, v)
---

Output:

---
<type 'int'> 18
<type 'long'> 189015844108
Traceback (most recent call last):

+ Trace 95913

---

The issue here is that:

  - The Python long type "represents numbers in an unlimited range"

  - pyg_type_from_object() maps the Python long type to G_TYPE_LONG

  - G_TYPE_LONG is limited to the size of the C long type - e.g. 32 
    bits on i386

  - Although it appears to the user that the list store should be able
    to hold any Python long (and therefore in an unlimited range), it can 
    in fact only hold a limited range of integers

I can see several options:

  1) Punt and put it down to an inconsistency that developers will get
     used to. Document the inconsistency.

  2) Deprecate the mapping of the Python long type to a gtype

  3) Map the Python long to a new gtype which can hold the Python object.
     Do our best to make sure that e.g. the int->text conversion happens 
     for CellRendererText and integer based sorting works correctly