@...BOX
 Draw a box on the screen
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 Syntax

     @ <nTop>, <nLeft>, <nBottom>, <nRight>
        BOX <cBoxString> [COLOR <cColorString>]

 Arguments

     <nTop>, <nLeft>, <nBottom>, <nRight> define the coordinates of the
     box.  @...BOX draws a box using row values from zero to MAXROW(), and
     column values from zero to MAXCOL(). If <nBottom> and <nRight> are
     larger than MAXROW() and MAXCOL(), the bottom-right corner is drawn off
     the screen.

     BOX <cBoxString> defines a string of eight border characters and a
     fill character.  If <cBoxString> is specified as a single character,
     that character draws the whole box.

     COLOR <cColorString> defines the display color of the drawn box.  If
     not specified, the box is drawn using the standard color setting of the
     current system color as defined by SETCOLOR().  Note that <cColorString>
     is a character expression containing the standard color setting.  If you
     want to specify a literal color setting, enclose it within quote marks.

 Description

     @...BOX draws a box on the screen using configurable border and fill
     characters.  @...BOX draws the box using <cBoxString> starting from the
     upper lefthand corner, proceeding clockwise and filling the screen
     region with the ninth character.  If the ninth character is not
     specified, the screen region within the box is not painted.  Existing
     text and color remain unchanged.

     After @...BOX executes, the cursor is located in the upper corner of the
     boxed region at <nTop> + 1 and  <nLeft> + 1.  ROW() and COL() are also
     updated to reflect the new cursor position.

 Examples

     .  These examples draw two boxes using box manifest constants
        defined in the supplied header file, Box.ch.  The first example draws
        a box using the specified characters for the border, but leaves all
        other areas of the screen intact.  The second example draws the same
        box filling the box region with space characters:

        #include "Box.ch"
        // Draw a box with a double-line top with a
        // single-line side
        @ 1, 1, 22, 79 BOX B_DOUBLE_SINGLE
        // Draw the same box filling the box region with
        // spaces
        @ 1, 1, 22, 79 BOX B_DOUBLE_SINGLE + SPACE(1)

 Files:  Library is CLIPPER.LIB, header file is Box.ch.