def text_field(name, row, column, length, editable=true)
      define_method(name) do
        platform.get_string(row, column, length)
      end

      define_method("#{name}=") do |value|
        platform.put_string(value, row, column)
      end if editable
    end
def text_field(name, row, column, length, editable=true)
      define_method(name) do
        platform.get_string(row, column, length)
      end

      define_method("#{name}=") do |value|
        platform.put_string(value, row, column)
      end if editable
    end
adds two methods to the screen object - one to set text in a text field,
 another to retrieve text from a text field.

 @example
   text_field(:first_name, 23,45,20)
   # will generate 'first_name', 'first_name=' method

 @param  [String] the name used for the generated methods
 @param [FixedNum] row number of the location
 @param [FixedNum] column number of the location
 @param [FixedNum] length of the text field
 @param [true|false] editable is by default true