如何在wxPython中平滑地移动项目？

Question

我正在尝试使用 wxPython 中的以下代码拖放一个按钮，但是，拖动会闪烁，并且感觉很刺耳，我不知道为什么——或者如何修复它。我仔细研究了 wxWidgets 文档，但似乎无法找出问题所在。提前致谢！

import wx

app = wx.App(False)
d = {}

def wMouseDown(e):
    print "!!!", e.GetEventObject()

def MouseDown(e):   
    o           = e.GetEventObject()
    sx,sy       = panel.ScreenToClient(o.GetPositionTuple())
    dx,dy       = panel.ScreenToClient(wx.GetMousePosition())
    o._x,o._y   = (sx-dx, sy-dy)
    d['d'] = o

def MouseMove(e):
    try:
        if 'd' in d:
            o = d['d']
            x, y = wx.GetMousePosition()
            o.SetPosition(wx.Point(x+o._x,y+o._y))
    except: pass

def MouseUp(e):
    try:
        if 'd' in d: del d['d']
    except: pass

frame = wx.Frame(None, -1, 'simple.py')
panel = wx.Panel(frame)
box = wx.BoxSizer(wx.VERTICAL)
button1 = wx.Button(panel, -1, "foo")
box.Add(button1, 0, wx.ALL, 10)
button2 = wx.Button(panel, -1, "bar")
box.Add(button2, 0, wx.ALL, 10)

button1.Bind(wx.EVT_LEFT_DOWN, MouseDown)
button2.Bind(wx.EVT_LEFT_DOWN, MouseDown)

button1.Bind(wx.EVT_MOTION, MouseMove)
button2.Bind(wx.EVT_MOTION, MouseMove)

button1.Bind(wx.EVT_LEFT_UP, MouseUp)
button2.Bind(wx.EVT_LEFT_UP, MouseUp)

panel.Bind(wx.EVT_MOTION, MouseMove)
panel.Bind(wx.EVT_LEFT_UP, MouseUp)

panel.SetSizer(box)
panel.Layout()
frame.Show()

app.MainLoop()