text: import tkinter as tk
  
  # --- functions ---
  
  def on_select(value):
      print('   value:', value, '--->', data[value])
      print('selected:', selected.get(), '--->', data[value])
  
  # --- main ---
          
  root = tk.Tk()
  
  # ---
  
  data = {
      "one": "Hello first World",
      "two": "Hello second World ",
      "three": "Hello third World",
  }    
  
  options = sorted(data)
  
  selected = tk.StringVar(value=options[0])
  
  #selected = tk.StringVar()
  #selected.set(options[0])
  
  op = tk.OptionMenu(root, selected, *options, command=on_select)
  op.pack()
  
  # ---
  
  root.mainloop()
  