[pygtk] Formatting floats in treeview

[Jeremy S]

If you put a float in a treeview, you get a really long decimal, which
is almost always not desired.  So, after playing around with it for a
while, I came up with this code to truncate floats at 1 decimal place:
            column.set_cell_data_func(renderer,
                lambda column, cell, model, iter:
cell.set_property('text', '%.1f' % model.get_value(iter,
column.get_sort_column_id())))

The problem with this is that it uses
GtkTreeViewColumn::get_sort_column_id() to get the column number,
which only works if the column is sortable.  Can anyone tell me what
to do if I want the formatting to work on any column, not just
sortable columns?  Thank you.