stable sort for gtk.TreeView+ListStore

[george young <gry ll mit edu>]

[pygtk-1.99.14, python-2.3a1, gtk+-2.2.0, linux]

I have a gtk.TreeView displaying a ListStore of four columns.
I need a *stable* sort by column so I can click on minor-key column
header, then major-key column header and have the rows sorted by
(major-key,minor-key).

Is there some way to replace the current sort algorithm?  Sorting is 
already a bit slow, so I'm afraid manual manipulation of rows in python
would be too slow (all right -- I *do* have 4400 rows and custom sort
compare function to get case-insensitive sort).

--george

-- 
 I cannot think why the whole bed of the ocean is
 not one solid mass of oysters, so prolific they seem. Ah,
 I am wandering! Strange how the brain controls the brain!
        -- Sherlock Holmes in "The Dying Detective"