Popup a verification screen from the function?

Popup a verification screen from the function?

I have a function that is called as a Custom Action on each row of a view. The function makes a change to a field in the corresponding record.  I would like to display a message for the user giving them a choice of OK or cancel.

Something like this

"You are about to change information for John Jones. Press OK to continue or Cancel to not make the change."

Is there a way to popup a verification screen from the function?

Herb Wexler