Input constraint not working on Windows GUI

I am trying out ‘Input Constraints’ but can't get it to work

Setup in SF:

Domain X of database type numeric(9,2)
on which i have defined an input constraint of type SQL, timing: On change. Constraint is X <> 0

I have a view with a column X (named equal to the domain) of type X

In the windows GUI in a form when i enter a value 0 for column X nothing happens. I was expecting an error message

Have i forgotten something or are Input constraints not supported for Windows GUI