在非OnPaint里应该使用ClientDC来画图

import wx

class Example(wx.Frame):
    def __init__(self, parent, title):
        super(Example, self).__init__(parent, title=title,
            size=(250, 150))

        wx.FutureCall(2000, self.DrawLine)

        self.Centre()
        self.Show()

    def DrawLine(self):
        dc = wx.ClientDC(self)
        dc.DrawLine(50, 60, 190, 60)

if __name__ == '__main__':
    app = wx.App()
    Example(None, 'Line')
    app.MainLoop()