Create a trigger that fires when closing an entry in entry view mode.
Just as there is an event that is triggered when opening a card in entry view mode. It would be interesting to have another event that fires when closing a card in entry view mode.
Scripts executed with Action, happen on a card in entry view mode. Having an event that fires when closing the card in entry view would allow me to automatically verify or rectify the actions done.
For example: I am creating a library that encrypts certain fields. With an Action script I enter the passphrase and it shows me the decrypted field. I would like that when I close the View Mode card, by means of a script, it automatically deletes the decrypted fields. Otherwise I have to delete them manually and it could happen that I forget and leave the fields exposed.