Screen Personas - Validation of a mandatory specific text field in MM01

Hello,

I want to add a specific mandatory field in MM01 using Screen Personas.

We are on Screen Personas 3.0 SP14.

Adding my logic in the Save button is working using this line of coding

session.findById("wnd[0]/sbar").setMessage("Field PartGroup in MRP3 is mandatory", "E");

But I cannot get the same blocking error if the user use the enter (I linked my validation to the onBeforeRefresh event)

Do you have a solution blocking the user whatever action he is doing (enter or click on save)?

Thank you in advance

Moez.