title: Tkinter objects are not centering
body: <p>I am trying to create a simple Python 3.x GUI project with tkinter, just to learn the language better (I started learning Python not long ago), of which the only thing it does is switching between different pages as a button is clicked. The problem is that the objects are not getting in the center of the screen. What's wrong in my code?</p>
  
  <p>Images:</p>
  
  <p><a href="https://i.stack.imgur.com/6Twpa.png" rel="nofollow noreferrer">Start Page</a></p>
  
  <p><a href="https://i.stack.imgur.com/RwhFl.png" rel="nofollow noreferrer">First Page</a></p>
  
  <p><a href="https://i.stack.imgur.com/ra9K2.png" rel="nofollow noreferrer">Second Page</a></p>
  
  <pre><code>import tkinter as tk
  
  LARGE_FONT = ("verdana", 10)
  
  
  class Application(tk.Tk):
      def __init__(self, *args, **kwargs):
          tk.Tk.__init__(self, *args, **kwargs)
          container = tk.Frame(self)
  
          container.grid()
  
          self.frames = {}
  
          for F in (StartPage, PageOne, PageTwo):
              frame = F(container, self)
              self.frames[F] = frame
              frame.grid(row=0, column=0, sticky="snew")
  
          self.show_frame(StartPage)
  
      def show_frame(self, cont):
          frame = self.frames[cont]
          frame.tkraise()
  
  
  class StartPage (tk.Frame):
      def __init__(self, parent, controller):
          tk.Frame.__init__(self, parent)
          label1 = tk.Label(self, text="Start Page", font=LARGE_FONT)
          label1.grid(row=0, column=0)
  
          button1 = tk.Button(self, text="Go to Page One",
                              command=lambda: controller.show_frame(PageOne))
          button1.grid(row=1, column=0)
  
          button2 = tk.Button(self, text="Go to Page Two",
                              command=lambda: controller.show_frame(PageTwo))
          button2.grid(row=2, column=0)
  
  
  class PageOne(tk.Frame):
      def __init__(self, parent, controller):
          tk.Frame.__init__(self, parent)
          label2 = tk.Label(self, text="Page One", font=LARGE_FONT)
          label2.grid(row=0, column=0, sticky="E")
  
          button2 = tk.Button(self, text="Go to Page Two",
                              command=lambda: controller.show_frame(PageTwo))
          button2.grid(row=1, column=0)
  
          button3 = tk.Button(self, text="Go to Start Page",
                              command=lambda: controller.show_frame(StartPage))
          button3.grid(row=2, column=0)
  
  
  class PageTwo(tk.Frame):
      def __init__(self, parent, controller):
          tk.Frame.__init__(self, parent)
          label2 = tk.Label(self, text="Page Two", font=LARGE_FONT)
          label2.grid(row=0, column=0,sticky="E")
  
          button2 = tk.Button(self, text="Go to Page One",
                              command=lambda: controller.show_frame(PageOne))
          button2.grid(row=1, column=0)
  
          button3 = tk.Button(self, text="Go to Start Page",
                              command=lambda: controller.show_frame(StartPage))
          button3.grid(row=2, column=0)
  
  
  app = Application()
  app.title("Application")
  app.mainloop()
  </code></pre>