title: Tkinter window that updates depending on the selection of the dropdown menu
body: <p>I want to make a GUI that updates once the choice in the dropdown menu is changed. The code below does this with a button, but the buttons and text that is called is not deleted every time the function is called. </p>
  
  <p>Update window without an additional button</p>
  
  <pre><code>from tkinter import *
  
  app = Tk()
  
  options = [
      "  ",
      "Expences",
      "Birds",
  ]
  
  
  clicked = StringVar()
  clicked.set(options[0])  # default value
  
  
  drop = OptionMenu(app, clicked, *options)
  drop.pack()
  
  
  def show():
      click = clicked.get()
  
      if click == "Expences":
          def Expences():
              b2 = Button(app, text="YESSSS!!!")
              b2.pack()
  
          Expences()
  
      elif click == "Birds":
          def Birds():
              a3 = Label(app, text="Maybe")
              a3.pack()
  
          Birds()
  
      else:
          return
  
  
  b1 = Button(app, text = "Click", command = show)
  b1.pack()
  
  app.minsize(400, 450)
  app.mainloop()
  </code></pre>