(form "00706" (size 40  6)
  (help "IMAGE_SELECT_TIP")
  (heading "Select Image")

  (label (position 2 3) (text "Image file name"))
  (field "image_file" (position 20 3) 
    (display_length 16) (input allowed) (max_length 256)
    (file input (extension "*.gif *.jpg *.jpeg *.tif *.bmp *.png")) (null disallowed)
  )

  (default_buttons)
)