OnFocus event for form components

Hello

I am trying to verify if there is or isnt focus events for form components. I havent been able to find it so far, and the only form rule triggers can be fired for events like change and exit.

Here is a basic explanation of what Im trying to do. Rather than create individual flows within a lengthy rule stack for various list components to obtain selectable list values and/ or the selected value stored in the database, I would much rather get/ set the selectable/ selected list values for a particular list box based on variables for the active field being set on focus of the active component. Hopefully that makes sense.

Thanks in advance

Jeremy