docs: def buttons(self, master):
          """Adds 'OK' and 'Cancel' buttons to standard button frame.
  
          Override if need for different configuration.
          """
  
          subframe = tk.Frame(master)
          subframe.pack(side=tk.RIGHT)
  
          ttk.Button(
              subframe,
              text="OK",
              width=10,
              command=self.ok,
              default=tk.ACTIVE
          ).pack(side=tk.LEFT, padx=5, pady=5)
  
          ttk.Button(
              subframe,
              text="Cancel",
              width=10,
              command=self.cancel,
              default=tk.ACTIVE
          ).pack(side=tk.LEFT, padx=5, pady=5)
  
          self.bind("<Return>", self.ok)
          self.bind("<Escape>", self.cancel)