无法多次调用tkinter GUI

Question

我的代码如下。

代码1：

  from Tkinter import *
    import Tkinter as tk2
    def call_second():
        import tk
        return
  root = Tk()
    E = tk2.Entry(root)
    E.pack(anchor = CENTER)
    B = Button(root, text = "OK", command = call_second)
    B.pack(anchor = S)
    root.mainloop()

代码2：

from Tkinter import *
import Tkinter as tk1
def close_window():
    global entry
    entry = E.get()
    print entry
    root1.destroy()
root1 = Tk()
E = tk1.Entry(root1)
E.pack(anchor = CENTER)
B = Button(root1, text = "OK", command = close_window)
B.pack(anchor = S)
root1.mainloop()

当我运行代码1时，按下ok按钮，它会调用第二个代码。当我关闭它并再次按下代码1上的按钮时，我无法再次调用GUI。