title: Why does this tkinter frame not surround both buttons
body: <p>Was playing around with python3 and tkinter. </p>
  
  <p>I was trying to have a frame with two labels in the frame. I wanted to draw a border around the frame and around each of the labels. </p>
  
  <p>As it is the below code shows the frame to only be around Label 1. Label 2 is below the notebook_Frame. 
  How do I make sure that widgets will be inside a specific frame?</p>
  
  <pre><code>import tkinter as tk
  
  def main():
      mainWinTk = tk.Tk()
      mainWinTk.title("Setup Server")
      mainWinTk.columnconfigure(0, weight=1)
      mainWinTk.rowconfigure(0, weight=1)
      mainWinTk.rowconfigure(1, weight=1)
  
      notebook_Frame = tk.Frame(mainWinTk, highlightbackground="green", highlightthickness=3, borderwidth=2, relief='ridge').grid(column=0, row=0, sticky=tk.W+tk.E+tk.S+tk.N)    
  
      tk.Label(notebook_Frame, text="Label 1", highlightbackground="red", highlightthickness=3).grid(column=0, row=0)
      tk.Label(notebook_Frame, text="Label 2", highlightbackground="red", highlightthickness=3).grid(column=0, row=1)
  
      mainWinTk.mainloop()
  if __name__ == "__main__":
      main()  
  </code></pre>