FUNCTION BXX()

  Short:
  ------
  BXX() Draws a box on the screen of a given color

  Returns:
  --------
  Nothing

  Syntax:
  -------
  Bxx(nTop,nLeft,nBottom,nRight,[nColor],[nShadow],;
                      [nShadowColor],[cFrame])

  Description:
  ------------
  <nTop >      - top row
  <nLeft>      - left col
  <nBottom>    - bottom row
  <nRight>     - right column
  [nColor]     - attribute to box default setcolor()
  [nShadow]    - numeric shadow type  (default 0)
                        follow numeric keypad
                            7 = upper left
                            1 = lower left
                            3 = lower right
                            9 = upper right
                            0 = no shadow

  [nShadowColor] - shadow attribute (default 7 - grey
  on black)

  [cFrame ] - frame string - MUST be 9 characters -
  default single line

  Examples:
  ---------
   BXX(10,10,20,20,47,9,8,"+-+|+-+| ")

  Source:
  -------
  S_BXX.PRG