Subtleties of using evKey

[Das Goravani]

I’m having trouble making a list of choices appear for Country.. 

I have a database of countries and I’m trying to provide a list of choices as they type the first few letters.

pKey is generated as an event BEFORE it updates the field value in the row.

If my field data name is iv1.Country so the data is being held in row iv1.. 

pKey is generated before it updates that row.. 

So I’m trying 

Con(iv1.Country,pkey) and it’s not working

Sometimes it puts two letters at the end of the one just typed.. because it got into the row this time before the event.. it seems it doesn’t have a reliable order of events.. 

So I type Bra and I end up with Braa

What is the subtlety of evKey.. how do you do a context sensitive help list with it?