top = Tk() # 创建顶级窗口
 
top.minsize(560, 545) # 最小尺寸
top.maxsize(560, 545) # 最大尺寸
 
top.mainloop()

# 此处省略父容器的定义 ...
 
# 定义下拉列表选项值集合
self.Combo5List = ['0', '1', '2', '3']
# 定义下拉列表Combobox
self.Combo5 = Combobox(self.Frame1, values=self.Combo5List, font=('宋体', 9), state='readonly')
# 放置控件
self.Combo5.place(relx=0.39, rely=0.636, relwidth=0.063, relheight=0.08)
# 设置下拉列表的默认值
self.Combo5.set(self.Combo5List[0])

# 新选项值的集合
index = ["a", "b", "c", "d"]
# 给Combobox的选项重新赋值
self.Combo5["value"] = index
# 设置默认值
self.Combo5.set(index[2])