set_cell_data_func - calling paradigm

[Nathan Schulte <reklipz gmail com>]

I've setup a TreeViewColumn with a CellRendererText that has the
set_cell_data_func callback setup.  Upon creation of a row(done upon
creation of the parent widget), this callback is invoked three times. 
It seems as though every time the row needs to be repainted (the cursor
is moved  in and out of the row), the callback is again invoked.

Without knowing the specific implementation of the TreeViewColumn and
CellRenderer architecture, this seems utterly unnecessary.  It seems as
though one would be better off just adding another Column to store the
textual representation of the data, alongside the data itself (this is
of course assuming that the "native" columns/cellrenderers (columns/cellrenderers
without an explicit set_cell_data_func callback setup) don't also
exhibit this behavior).

Is this behavior normal?  If so, would someone mind explaining
why?  If not would anyone care to enlighten me as to where lay my
mistake(s)?

Thanks!
-Nate