title: Tkinter, treeview doesn't resize with window
body: <p>How can I make Treeview resize and keep the Sizegrip in the se corner of the window when I resize the window vertically and horizontally?  I have used frames, set sticky="ns" to resize Frame in window and fill='BOTH', expand=True to resize Treeview in Frame.</p>
  
  <pre><code>from tkinter import *           # Python interface to the Tk GUI toolkit
  from tkinter import filedialog  # open file
  from tkinter import ttk         # Tk themed widget set
  
  root = Tk()
  
  #menu itmes removed for space
  
  win2 = Toplevel(master=root)    # create a new top level window
  frame1 = Frame(win2)
  frame2 = Frame(win2)
  frame3 = Frame(win2)
  scrollbar = Scrollbar(frame1)     # put a scrolbar widget on the right side of the window
  scrollbar.pack(side = RIGHT, fill = Y)
  sizegrip=ttk.Sizegrip(frame3)     # put a sizegrip widget on the southeast corner of the window
  sizegrip.pack(side = RIGHT, anchor = SE)
  
  # put a treeview widget on the window with stylized column headers and use show="headings" to hide the first hierarchy column
  column_headers=['PID', 'Name', 'DNA Company Name', 'DNA User Name', 'Admin Name', 'Email']
  style = ttk.Style()
  style.configure("Treeview.Heading", font=("Verdana", 11))
  tv = ttk.Treeview(frame1, height=30, columns=column_headers, show="headings", yscrollcommand = scrollbar.set) 
  tv.pack(side=LEFT, fill=BOTH, expand=TRUE)
  scrollbar.config(command = tv.yview)
  
  export_button = ttk.Button(frame2, text = "Export", width=15,command=win2.destroy)
  export_button.pack(side = LEFT, anchor = E, padx=5, pady=5)
  
  close_button = ttk.Button(frame2, text = "Close", width=15, command=win2.destroy)
  close_button.pack(side = RIGHT, anchor = W, padx=5, pady=5)
  
  tv.heading('PID', text='PID')
  tv.column('PID', anchor='w', width = 80)
  
  tv.heading('Name', text='Name')
  tv.column('Name', anchor='w')
  
  tv.heading('DNA Company Name', text='DNA Company Name')
  tv.column('DNA Company Name', anchor='w')
  
  tv.heading('DNA User Name', text='DNA User Name')
  tv.column('DNA User Name', anchor='w')
  
  tv.heading('Admin Name', text='Admin Name')
  tv.column('Admin Name', anchor='w')
  
  tv.heading('Email', text='Email')
  tv.column('Email', anchor='w')
  
  frame1.grid(column=0, row=0, sticky="ns")
  frame2.grid(column=0, row=1, sticky="n")
  frame3.grid(column=0, row=2, sticky="se")
  root.rowconfigure(0, weight=1)
  
  root.mainloop()
  </code></pre>