Hi,
The formal answer would be: SDK coding is necessary.
However, if your logic is as simple as the price not the same as the default price, FMS could be tried to select a defined message. Something like:
SELECT 'You have changed the price, do you want to continue? '
FROM OITM T0
JOIN ITM1 T1 ON T1.ItemCode=T0.ItemCode
WHERE T0.ItemCode=$[$38.1.0] and T1.PriceList= (SELECT T2.ListNum FROM OCRD T2 WHERE T2.CardCode=$[$4.0.0]) AND T1.Price != $[$38.17.number]
Thanks,
Gordon