Using screen actions on change of a value in an editable table

I am using the editable table widget and have a situation where the acceptable values and mandatory settings of one field are dependant on the value of another field.

I have these settings working well when the table is loaded with existing values, but I want to re-use a screen action which populates the acceptable values as the user types into the table.

Is there a way of calling a screen action when a value changes in a row in the table,

Thanks in anticipation. Regards, Alan