def __init__(self, parent, id, model):
        wx.ScrolledWindow.__init__(self, parent, id, style=wx.NO_FULL_REPAINT_ON_RESIZE)
        self.model = model
        self.node_dict = {}
        self.link_dict = {}
        self.node_size = 25
        self.dragNode = None
        self.dragImage = None
        self.queue = event_queue()