The scroll bar will be visible if at least the right border is selected for the field (assuming thisis the same as how it works in FMP11), but you won't be able to scroll the scroll bar unless browse mode access is permitted in field behavior settings.
The workaround to use to get a read only field with a working scroll bar is to use a calculation field formatted with a scroll bar to display the contents of your text field.
Thank you it works with a calculation field.
Now I have another question. What do you usually do to change a table structure at a customer location if you cannot have his files to modify it manually. I need to send him a "program" to do that.
Create a new version of the file, include a script that imports all data from the users current file into the new file. If you design such solutions to use the Data Separation Model: Convert to Seperation Model you can greatly reduce how often you need to do such imports. (But of course a stucture change to a table is a case where you have to set up the import.)
Such imports should also update serial number field settings so that their next serial value will be greater than that of any data just imported. This can also be part of the script.
If you set this up correctly, the user can simply click a button to start the process, then select the original file in a dialog box and the rest is an automatic update and they can replace their old file with the new after the script finishes execution.