INVERTATTR()
 Inverts the foreground and background of an attribute
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 Syntax

     INVERTATTR(<cAttr|nAttr>) --> nInvertAttr

 Argument

     <cAttr|nAttr>  Designates the attribute to process.

 Returns

     INVERTATTR() returns the value of the inverted attribute.

 Description

     INVERTATTR() returns a value that corresponds to the opposite of an
     individual screen attribute.  This is same as if you were to exchange
     the foreground color for the background.  For example, red characters on
     a white background, become white characters on a red background.

     This new attribute can be used in conjunction with such functions as
     SCREENATTR(), COLORWIN(), and COLORREPL().

 Notes

     .  The flashing and high-intensity attributes are not affected.

     .  The result is always numeric, regardless of the parameter's
        data type.

 Examples

     .  Invert the attributes at the current cursor position.  In
        doing so, the attribute is not set:

        ? INVERATTR(SCREENATTR())

     .  You can represent the attribute in a number of different ways.
        The returned value is always numeric:

        8                           // Result:  30

     .  An invalid attribute:

        ? INVERTATTR("xx/yy")       // Result:  0