GRAPHBACKGROUND        Set Graphics Background Color                 pp 166

 Syntax:  GraphBackground (Color) ;

 Type:    Integer

 Form:    Procedure

 Purpose: Set graphics background color in range of 0..15.

 Colors:  0: Black        4: Red           8: DarkGray      12: LightRed
          1: Blue         5: Magenta       9: LightBlue     13: LightMagenta
          2: Green        6: Brown        10: LightGreen    14: Yellow
          3: Cyan         7: LightGray    11: LightCyan     15: White


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 Usage:
       BEGIN
          GraphColorMode      ;   { Set 320x200 graphics mode }
          GraphBackground (1) ;   { Set background to blue    }
       END.