We have a requirement to allow users to select points on the xamDataChart.  We have already implemented a tool for doing a rectangular selection.  Now our clients are asking for the ability to draw an irregular polygon to use for the selection boundary.  Basically you'd click to define each point on the polygon, with a "rubberband" connecting the already drawn points to the mouse location.  A double click would set the last point on the polygon and start the search.  

Would you have any suggestions on how we could implement such a tool?  Since there wasn't a rectangle tool per se, we're using OnAttemptedScaleChanged() to get the rectangle selection values as someone there suggested a couple of years ago, but we're not sure how we'd go about handling polygons, or determining if a point falls within the polygon.

Thanks!