Dialog is corrupt if too many items

[eight04]

#! python3

from tkinter import *
from tkinter.ttk import *
from comiccrawler.gui import select_episodes
from comiccrawler.core import Mission, Episode

# create fake mission

episodes = [Episode("some title #{}".format(i)) for i in range(7 * 1000)]
mission = Mission("Fake mission", "http://www.pixiv.net/", episodes)

def test():
    select_episodes(root, mission)

root = Tk()

Button(root, text="test", command=test).pack()

root.mainloop()

With 10k+ items, the dialog doesn't show.

[eight04]

After 2016.3.27, the dialog is not corrupt but: