Screen()

         Clears the screen with optional color and string

    Syntax:

         Screen( [cString], [cColor] ) -> Nil

         cString : String to fill up the screen
         cColor  : Optional color.

    Description:

         Clears the screen with optional string and color.

    Return:

         Nothing.

    Example:

         Screen()                          // usual cls
         Screen( "Fast Library " )         // cls with string
         Screen( "Fast Library ", "R/B" )  // cls with string and color