Output a blank box with a title
──────────────────────────────────────────────────────────────────────────────

 Syntax

        H_BlankBox( cHeader , nCol )
  
 Arguments:

      cHeader - Heading
      nCol    - Column at which to output heading ( -1 to centre )

 Returns:

      NIL

 Description:

      Outputs a standard double lined screen shell
      cHeading appears on row 3, at the position given by nCol

 Examples:

      Output a blank box with a centred title :

          H_BlankBox( "Title" , -1 )

 Header File: H_LIB52.CH

 Source: BLANKBOX.PRG

 Author:  Martin Colloby