1) create a new component based on combo box
2) override it's set data(value:Object) function
3) the 'value' parameter to this function has the selected
data from the datasourece. I think it's current row. But off the
top of my head I'm not sure.
4) get the value for this column, search it in the underlying
datasource of the combobox
5) if found, set the selected index of the combo box to the