Scatter plot data series ordering should move series to the front/back

Right now there does not seem to be a way to change which data series are in the front/back of a scatter plot with multiple data series.  Instead, I have to add the data in the order I want it to appear.  The up/down arrows in the 'Select Data Source' window should allow one to change the order of appearance of each data series and move them to the front/back of the chart.