dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
biv = dt << Run Script( "Bivariate" );
Wait( 0 );
pickColor = Pick Color();
Report( biv )[AxisBox( 1 )] <<
Add Ref Line( 105, "Dashed", pickColor, "Mean" );
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
biv = dt << Run Script( "Bivariate" );
Wait( 0 );
pickColor = Pick Color( "Select a Line Color", "BlueGreen" );
Report( biv )[AxisBox( 1 )] <<
Add Ref Line( 105, "Dashed", pickColor, "Mean" );
picked color = Pick Color( "Select a Background Color", "BlueGreen" );
New Window( "Example",
       gb = Graph Box(
              Frame Size( 300, 300 ),
              Marker( Marker State( 3 ), [11 44 77], [75 25 50] );
              Line( [10 30 70], [88 22 44] );
       )
);
gb[FrameBox(1)] << Background Color ( picked color );
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
biv = dt << Run Script( "Bivariate" );
Wait( 0 );
pickColor = Pick Color( "RGB", RGBCOLOR( 1/*red*/, 0/*green*/, 1/*blue*/ ) );
Report( biv )[AxisBox( 1 )] <<
Add Ref Line( 105, "Dashed", pickColor, "Mean" );

Help created on 10/11/2018