COLORWIN()
 Exchanges particular attributes in a screen area
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 Syntax

     COLORWIN([<nTopLine>], [<nLeftCol>],
        [<nBottomLine>], [<nRightCol>],
        [<cNewAttr|nNewAttr>], [<cOldAttr|nOldAttr>])
         --> cNull

 Arguments

     <nTopLine>  Designates the topmost line to begin processing.  The
     default is the cursor line.

     <nLeftCol>  Designates the leftmost column to begin processing.  The
     default is the cursor column.

     <nBottomLine>  Designates the bottommost line that is processed.
     The default is the last screen line or window line.

     <nRightCol>  Designates the rightmost column to clear.  The default
     is the right screen border or window border.

     <cNewAttr|nNewAttr>  Designates the new attribute to replace the old
     one.  The default is the standard attribute CLEARA.

     <cOldAttr|nOldAttr>  Designates the old character to exchange.  The
     default is "exchange all attributes".

 Returns

     COLORWIN() always returns a null string.

 Description

     COLORWIN() exchanges all occurrences of <cOldAttr|nOldAttr>for the
     <cNewAttr|nNewAttr> attribute, within a particular screen or window
     area.  The function operates in a similar way to COLORREPL(), except
     with COLORWIN() you can define the screen area to work on.

     The parameters <nTopLine> and <nLeftCol> define the row and column for
     the top-left corner; <nBottomLine> and <nRightCol> define the row and
     column for the bottom-right column.

 Note

     .  If <cOldAttr|nOldAttr> is not specified, all attributes are
        exchanged for <cNewAttr|nNewAttr>; if <cNewAttr|nNewAttr> is not
        specified, the attributes are exchanged for CLEARA.

 Examples

     .  Exchange attribute 7 (white on black) for 0 (black on black =
        invisible) from the current cursor position to the end of the screen
        area:

        COLORWIN(0, 7)

     .  Exchange all attributes in the area from line 23, column 15 to
        line 24, column 70 for the standard attribute CLEARA:

        COLORWIN(23, 15, 24, 70)

     .  Replace all attributes for attribute 116 (red on white) in the
        region from line 23, column 15 to line 24, column 70:

        COLORWIN(23, 15, 24, 70, 116)

     .  Change the white on black display to black on white.  You can
        specify different parameters:

        COLORWIN(23, 15, 24, 70, "0/7", "7/0")

     .  Mixed formats are also possible:

        COLORWIN(23, 15, 24, 70, "0/7", 7)