Python tkSimpleDialog askquestion方法导致窗口挂起

我试图使用键盘事件绑定从tkSimpleDialog调用askquestion方法，但它总是导致窗口挂起在MacOSX中

如果我从菜单中选择“查找”选项，它将正常工作，但每当我尝试使用键盘事件调用它时，窗口将挂起

问题出现在“编辑”菜单部分的最后一个绑定事件和“查找”命令函数中

有人知道这是怎么发生的或为什么发生的吗

提前谢谢你的帮助

import Tkinter as tk
import ScrolledText
import tkFont
import tkFileDialog
import tkSimpleDialog
from ScrolledText import *
from Tkinter import *
import tkMessageBox
from tkSimpleDialog import askstring


#A very simple text editor
class SimpleTextEditor:

    def __init__(self, parent):
        self.parent = parent
        self.parent.title("TextPerfect")
        self.textWidget = ScrolledText(parent, width=80, height=50, font=(tkFont.Font(family= "Consolas", size= "12")))
        self.textWidget.pack()

        self.menuBar = tk.Menu(parent, tearoff=0)
        # About Menu
        self.about_menu = tk.Menu(self.menuBar, tearoff= 0)
        self.menuBar.add_cascade(label= "Text Perfect", menu= self.about_menu)
        self.about_menu.add_command(label= "About", command= self.about_command)
        self.about_menu.add_command(label= "Quit", command= self.exit_program, accelerator="Cmd+W")
        self.parent.bind_all("<Command-w>", self.exit_program)
        self.parent.bind_all("<Command-W>", self.exit_program)

        # File Menu
        self.file_menu = tk.Menu(self.menuBar, tearoff = 0)
        self.menuBar.add_cascade(label = "File", menu=self.file_menu)
        self.file_menu.add_command(label="New", command=self.new_command, accelerator="Cmd+N")
        self.parent.bind_all("<Command-n>", self.new_command)
        self.parent.bind_all("<Command-N>", self.new_command)
        self.file_menu.add_separator()
        self.file_menu.add_command(label="Open", command=self.open_command, accelerator="Cmd+O")
        self.parent.bind_all("<Command-o>", self.open_command)
        self.parent.bind_all("<Command-O>", self.open_command)
        self.file_menu.add_command(label="Save", command=self.save_command, accelerator="Cmd+S")
        self.parent.bind_all("<Command-s>", self.save_command)
        self.parent.bind_all("<Command-S>", self.save_command)
        self.file_menu.add_command(label="Save As...", command=self.saveAs_command, accelerator="Cmd+Shift+S")
        self.parent.bind_all("<Command-Shift-s>", self.saveAs_command)
        self.parent.bind_all("<Command-Shift-S>", self.saveAs_command)

        # Edit Menu
        self.edit_menu = tk.Menu(self.menuBar, tearoff=0)
        self.menuBar.add_cascade(label= "Edit", menu= self.edit_menu)
        self.edit_menu.add_command(label = "Cut", command = self.cut_command, accelerator="Cmd+X")
        self.parent.bind_all("<Command-Shift-x>", self.cut_command)
        self.parent.bind_all("<Command-Shift-X>", self.cut_command)
        self.edit_menu.add_command(label = "Copy", command = self.copy_command, accelerator="Cmd+C")
        self.parent.bind_all("<Command-Shift-c>", self.copy_command)
        self.parent.bind_all("<Command-Shift-C>", self.copy_command)
        self.edit_menu.add_command(label = "Paste", command = self.paste_command, accelerator="Cmd+V")
        self.parent.bind_all("<Command-Shift-v>", self.paste_command)
        self.parent.bind_all("<Command-Shift-V>", self.paste_command)
        self.edit_menu.add_separator()
        self.edit_menu.add_command(label= "Find", command= self.find_command, accelerator="Cmd+F")
        self.parent.bind_all("<Command-f>", self.find_command) #<-------HERE------
        self.parent.bind_all("<Command-F>", self.find_command)

        parent.config(menu=self.menuBar)

##################################################

    def open_command(self, event=None):
        file = tkFileDialog.askopenfile(parent=root,mode='rb',title='Select a file')
        if file != None:
            contents = file.read()
            self.textWidget.insert("1.0",contents)
            file.close()

    def save_command(self, event=None):
        file = tkFileDialog.asksaveasfile(mode= 'w')
        if file != None:
            data = self.textWidget.get("1.0", END+'-1c')   #strip trailing \n at EOF
            file.write(data)
            file.close()

    def saveAs_command(self, event=None):
        file = tkFileDialog.asksaveasfile(mode= 'w')
        if file != None:
            data = self.textWidget.get("1.0", END+'-1c')   #strip trailing \n at EOF
            file.write(data)
            file.close()

    def exit_program(self, event=None):
        if tkMessageBox.askokcancel("Quit", "Are you sure you want to quit?"):
            self.parent.destroy()

    def new_command(self, event=None):
        print "new"

    def cut_command(self, event=None):
        text = self.textWidget.get(SEL_FIRST, SEL_LAST)
        self.textWidget.delete(SEL_FIRST, SEL_LAST)
        self.textWidget.clipboard_clear()
        self.textWidget.clipboard_append(text) 

    def copy_command(self, event=None):
        text = self.textWidget.get(SEL_FIRST, SEL_LAST)
        self.textWidget.clipboard_clear()
        self.textWidget.clipboard_append(text)

    def paste_command(self, event=None):
        try:
            text = self.textWidget.selection_get(selection= 'CLIPBOARD')
            self.textWidget.insert(INSERT, text)
        except TclError:
            pass

    def find_command(self, event=None):
        target = askstring('SimpleEditor', 'Search String?')    #<----AND HERE-----
        if target:
            where = self.textWidget.search(target, INSERT, END)
            if where:
                print where
                pastit = where + ('+%dc' % len(target))
                self.textWidget.tag_add(SEL, where, pastit)
                self.textWidget.mark_set(INSERT, pastit)
                self.textWidget.see(INSERT)
                self.textWidget.focus()       

    def about_command(self):
        label = tkMessageBox.showinfo("About", "A super duper simple text editor. It's now available through github, thanks to Jason!")                


    #dummy function as a place holder while constructing further functionality        
    def dummy_funct(self, event=None):
        print"The life of a function is often very lonely..."

if __name__ == "__main__":
    root = tk.Tk()
    textApp = SimpleTextEditor(root)
    root.mainloop()