In layout mode, layout>>Layout Setup >> "General" Tab >> the little check box that says "Show field frames when record is active"
would you also have an answer to my second question?
" in the original input layout, I still can modify the content of these picklists in the reference layout. That was not the idea of references. Although I can see the logic, why this is happening, I do not understand of how to prevent the modification of selected fields only in the reference layout."
I think you need to explain your second question in more detail. Normally, one would expect to be able to edit data stored in a database unless the interface and/or security settings (their privilege set) prevents the user from doing do. But the devil is in the details. We don't have a clear idea of what you mean by a "reference layout".
I have the same question as Phil, but I make the assumption that you want a data entry dialog, then a reference only "original layout".
If so, simply make the fields not enterable in browse mode (Inspector...data tab)
thanks Phil ...
while I was typing away an answer to you, I received the solution that worked from 'Ninja'
thanks to both of you