[pygtk] Formatting a spinbutton's display

[Jeremy S]

I would like to use a spinbutton but instead of just displaying a
float or integer, I want the display to be formatted.  In my case I
want it to be formatted as currency ($ in front and commas separating
thousands, millions, etc.), but I can't even find any information on
how to tackle this problem generally.

I know for treeviews this type of thing can be accomplished with
set_cell_data_func.  Is there anything similar for spinbuttons?