FUNCTION MESSYN()

  Short:
  ------
  MESSYN() Popup YesNo prompt box

  Returns:
  --------
  <lYes> => True for yes, False for No

  Syntax:
  -------
  MESSYN(cQuestion,[cYes],[cNo],[nTop],[nLeft])

  Description:
  ------------
  Pops up a box and displays a question <cQuestion>
  and two prompts.

  [cYes] ,[cNo] are optional prompts 1 and 2. Default
  is YES/NO.

  [nTop] and [nLeft] are optional box top and left
  coordinates. Default is centered.

  Examples:
  ---------
   if messyn("Are you done")

   if messyn("Are you done","Not yet","Almost",10,10)

   if messyn("Are you done","Not Yet","Almost")

  Source:
  -------
  S_MESSYN.PRG