how to store wxGrid cell values?

In an application, I pop up a wxDialog having a wxGrid.

If I edit a wxGrid cell and then press <enter>, or if I move to another cell, EVT_GRID_CELL_CHANGE is called and all is well. OTOH, if I edit a cell, and then press the "OK" button of the wxDialog, what I wrote in the cell is not saved (EVT_GRID_CELL_CHANGE is not called).

How can I fix this? Users typically type something on a cell and then go straight to clicking on the wxDialog "OK" without pressing <enter>.

I'm using Python 2.3.2, wxPython 2.4.2.4.

Thanks,
Davide