How to customize data points on a Flex graph?

I have an area graph and I'm looking to have the data points to be shown. I have a CircleItemRenderer, but this shows all of the datapoints in the default stroke and fill.

1) How do I customize the display of my CircleItemRenderer? (instead of it having a开发者_StackOverflow中文版n orange fill, how can I change the color?

2) How can I decide to show the node for specific data points but not for others? For example, in my .XML file that imports the data for the graph, I may have a variable show_data_point which is true or false.

Here's the current code I have:

            <mx:AreaSeries
                yField="numbers"
                form="segment"
                displayName="area graph"
                areaStroke = "{darkblue}"
                areaFill="{blue}"
            >

            <mx:itemRenderer>
                    <mx:Component>
                            <mx:CircleItemRenderer/>
                    </mx:Component>
            </mx:itemRenderer>

              </mx:AreaSeries>      
        </mx:series>

Thanks a lot for your help!

1. You can implement your own item renderer that should implement IDataRenderer interface and be an ascendant of ProgrammaticSkin.
2. According to documentation there is a fill style for the series which is applied to the fill of circle point.