You can get 3D-looking fields in a layout region to make your form more appealing. I found this out by accidentally overlaying a text field on a combobox field.
In a layout region, create a combobox field and a text field. Set the following parameters for the combobox field:
width = width of text field + .030"
left = left of text field - .020"
height = height of text field + .031"
top = top of text field - .010 "
The text field should now be sitting on top of the combobox. Click on the text field and select Design->Bring to Front.
You might have to play with the font size of the text field.