Warning Message Popup after BusComp_Set event

Hi,

We have a requirement to show warning message when a value is entered in a field and context moves to next field (tab),

Current behaviour: On entering value, few operations done at the preset event and then field moves to read only

Expected Change: On entering value, few operations done at the preset event, then field moves to read only and then a warning message should popup

Is there any OOB feature to achieve above req? or any other way?

Note: Openui is enabled :-) so the solution should work in openui as well

Thanks,

Pugal