为什么要使用wxPython's EVT_KILL_FOCUS的行为出乎意料

Question

我希望我的wxPython应用程序在文本输入小部件失去焦点时触发事件。我遵循了这里的教程，其中描述了使用wx.EVT_KILL_FOCUS。然而，我得到了意想不到的行为

以下代码运行良好：

import wx
class MyForm(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self, None, wx.ID_ANY, "Focus Tutorial 1a")
        panel = wx.Panel(self, wx.ID_ANY)
        txt = wx.TextCtrl(panel, wx.ID_ANY, "")
        txt.Bind(wx.EVT_KILL_FOCUS, self.onTextKillFocus)
        """
        This next line seems to be important for working correctly,
        but I don't understand why:
        """
        txt.Bind(wx.EVT_SET_FOCUS, self.onTextFocus)
        btn = wx.Button(panel, wx.ID_ANY, "Test")
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(txt, 0, wx.ALL, 5)
        sizer.Add(btn, 0, wx.ALL, 5)
        panel.SetSizer(sizer)
    def onTextFocus(self, event):
        print "text received focus!"
    def onTextKillFocus(self, event):
        print "text lost focus!"
if __name__ == '__main__':
    app = wx.App()
    frame = MyForm().Show()
    app.MainLoop()

当我从文本控件来回切换到按钮，或者点击文本控件的内部或外部时，我会收到我想要的焦点消息。

然而，当我进行以下（合理的？）编辑时，情况会恶化：

import wx
class MyForm(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(self, None, wx.ID_ANY, "Focus Tutorial 1a")
        panel = wx.Panel(self, wx.ID_ANY)
        txt = wx.TextCtrl(panel, wx.ID_ANY, "")
        txt.Bind(wx.EVT_KILL_FOCUS, self.onTextKillFocus)
        """
        This next line seems to be important for working correctly,
        but I don't understand why:
        """
##        txt.Bind(wx.EVT_SET_FOCUS, self.onTextFocus)
        btn = wx.Button(panel, wx.ID_ANY, "Test")
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(txt, 0, wx.ALL, 5)
        sizer.Add(btn, 0, wx.ALL, 5)
        panel.SetSizer(sizer)
    def onTextFocus(self, event):
        print "text received focus!"
    def onTextKillFocus(self, event):
        print "text lost focus!"
if __name__ == '__main__':
    app = wx.App()
    frame = MyForm().Show()
    app.MainLoop()

意外的行为是，当我尝试将焦点从文本框更改为其他任何内容（选项卡或鼠标单击）时，'text lost focus!'消息将打印一次，再也不会打印，并且我无法再编辑文本控件的内容。

这是预期行为吗？如果没有，我做错了什么

Python版本2.7，wxPython版本3.0.0.0，Windows 7 64位

Answer 1

正如wxEvent:：Skip（）文档中所解释的，您几乎应该总是为非命令事件调用它，因为您不想阻止默认处理的发生。