import tkinter as tk

def tk_04():
    """Create a window that will ask the user to enter a name in a text box.
       When they click on a button it will add it to the end of the list that is
       displayed on the screen. Create another button which will clear the list."""
    def click():
        name = txt_in_box.get()
        if name != "":
            lst_names.insert('end', name)
            txt_in_box.delete(0, 'end')
        txt_in_box.focus()

    def reset():
        lst_names.delete(0, 'end')
        txt_in_box.focus()

    window = tk.Tk()
    window.title("Lista TK")
    window.geometry("390x350")

    lbl_info = tk.Label(text="Ingresa un nombre: ")
    lbl_info.place(x=40, y=25, width=150, height=35)

    txt_in_box = tk.Entry()
    txt_in_box["justify"] = "center"
    txt_in_box.place(x=180, y=25, width=150, height=35)
    txt_in_box.focus()

    btn_add = tk.Button(text="Agregar", command=click)
    btn_add.place(x=40, y=75, width=150, height=35)
    btn_reset = tk.Button(text="Vaciar", command=reset)
    btn_reset.place(x=190, y=75, width=150, height=35)

    lst_names = tk.Listbox()
    lst_names.place(x=40, y=120, width=300, height=200)
    
    window.mainloop()