Draws the frame. This method is called by the
DialPlot class,
you shouldn't need to call it directly.
Parameters: g2 - the graphics target (null not permitted). Parameters: plot - the plot (null not permitted). Parameters: frame - the frame (null not permitted). Parameters: view - the view (null not permitted).
Returns the shape for the window for this dial. Some dial layers will
request that their drawing be clipped within this window.
Parameters: frame - the reference frame (null not permitted). The shape of the dial's window.