using two layouts/ in order to play with field behavior looks really a very heavy and hard maintenance way of working to me.
so I was naturally looking for a simple function that would to that easily. Apparently FileMaker developers don't care about this.
i So do hope I'm wrong in my statement.
So in case someone has The Great Solution I guess I have no other choice but double my field with one toggle script to hide/show it.
I Just want to make a field editable or not depending of a value that is entered in another field.