Python tkinter frame alignment
<p><a href="http://i.stack.imgur.com/BqeRS.png" rel="nofollow">My GUI</a></p>

<p>How can I place my <code>cb_frame</code> ideally vertically, aligned to the left? When text after some checkbutton has other length than other texts, this checkbutton is then uneven relative to the others. I used <code>place</code> instead of <code>pack</code> in <code>cb_frame</code> because I don't know how to put the frame with checkbuttons in this place by <code>pack</code>.</p>

<pre><code>import Tkinter

class MyGUI:  
    def __init__(self):
        self.main_window = Tkinter.Tk()
        self.main_window.title("My GUI")
        self.main_window.geometry("520x350+500+480")

        self.first_frame = Tkinter.Frame()
        self.second_frame = Tkinter.Frame()
        self.third_frame = Tkinter.Frame()
        self.cb_frame = Tkinter.Frame()

        self.first_frame.pack(fill="x", padx="3", pady="3")
        self.second_frame.pack(fill="x", padx="3", pady="3")
        self.third_frame.pack(fill="x", padx="3", pady="3")
        self.cb_frame.place(x="220")

        self.btn_1 = Tkinter.Button(self.first_frame, text="Button 1", bg="blue", width="12", height="4", command=None)
        self.btn_2 = Tkinter.Button(self.first_frame, text="Button 2", bg="blue", width="12", height="4", command=None)
        self.btn_3 = Tkinter.Button(self.second_frame, text="Button 3", bg="green", width="12", height="4", command=None)
        self.btn_4 = Tkinter.Button(self.second_frame, text="Button 4", bg="green", width="12", height="4", command=None)
        self.btn_5 = Tkinter.Button(self.third_frame, text="Button 5", bg="orange", width="12", height="4", command=None)
        self.btn_6 = Tkinter.Button(self.third_frame, text="Button 6", bg="orange", width="12", height="4", command=None)

        self.btn_1.pack(side="left")
        self.btn_2.pack(side="left", padx="2")
        self.btn_3.pack(side="left")
        self.btn_4.pack(side="left", padx="2")
        self.btn_5.pack(side="left")
        self.btn_6.pack(side="left", padx="2")

        self.cb_var1 = Tkinter.IntVar()
        self.cb_var2 = Tkinter.IntVar()
        self.cb_var3 = Tkinter.IntVar()
        self.cb_var4 = Tkinter.IntVar()

        self.cb_var1.set(0)
        self.cb_var2.set(0)
        self.cb_var3.set(0)
        self.cb_var4.set(0)

        self.cb1 = Tkinter.Checkbutton(self.cb_frame, text="1000", variable=self.cb_var1).pack()
        self.cb2 = Tkinter.Checkbutton(self.cb_frame, text="2000", variable=self.cb_var2).pack()
        self.cb3 = Tkinter.Checkbutton(self.cb_frame, text="3000", variable=self.cb_var3).pack()
        self.cb4 = Tkinter.Checkbutton(self.cb_frame, text="over 4000", variable=self.cb_var4).pack()

        Tkinter.mainloop()

my_gui = MyGUI()
</code></pre>