Tkinter refresh

[eduardoforo]

def selmunicipio():
    top = tk.Toplevel()
    top.title("Selección de Municipio")
    y=1
    for i in listamunicipios:
        y+=1
        if y<=30:
            tk.Radiobutton(top,text=i,variable=municipio,value=i).grid(row=y, column=0, sticky='w')
        else:
            tk.Radiobutton(top,text=i,variable=municipio,value=i).grid(row=y-29, column=1, sticky='w')
    button = tk.Button(top, text="Elige y pulsa aquí", command=top.destroy)
    button.grid(row=1, column=0)
tk.Entry(raiz, textvariable=municipio, validate='focus', validatecommand=selmunicipio).grid(row=11, column=1, sticky='w,e', padx=5, pady=5)

When I focus on the Entry, a window is displayed, I choose an option, I press a button and it appears in the Entry.
But once the operation is done, when I return to focus, the window does no appears again.
How can I restart the Entry?

Thanks.