def __init__(self, model, color = 'BLUE'):
        self.node_radius = 10 # Radius of a node
        self.node_color = 'GREEN'    # TODO not currently used
        self.node_outline = 'BLACK'  # TODO not currently used
        # Setting this flag prevents drawing this node and links while dragging
        self.dragging = False        

        self.model = model

        # Now setup the node's bitmap so we can just blit to the screen
        # rather than having to re-draw every time.
        #self.bmp = wx.EmptyBitmap(2 * self.node_radius + 4, 2 * self.node_radius + 4)
        self.bmp = wx.EmptyBitmap(2 * self.node_radius, 3 * self.node_radius)