If it is just printing you need to see all the data in the text field you would be better off setting up a seperate print layout and if needed using sliding and printing to reduce the size of the field and move any othe robjects under it up.
On your layout set the field to be as long as you think you need it to be for the maximum height, and by using Sliding and Printing settings you can have this reduce when the layout is being printed.
In layout mode, click on your text field and go: Format > Set Sliding/Printing...
When the Set Sliding/Printing dialog pops-up tick 'Sliding up based on' and 'Also reduce the size of the enclosing part'
Now when you print that field and the part of the layout will reduce to the amount of text, or other objects on the layout.
Alternatively if you are using FileMaker 10 you could run a script whenever a user clicks out of a field that reduces the font size, however if you were to reduce the text you may get to a point where it is unreadable.
I hope this helps.
Thanks for your reply.
I am also interrested in that the text downscale on the monitor. How do i on the most easy way setup the script.