import tkinter


def run():
	model_menu.entryconfig("Run model", state="disable")
    
root = tkinter.Tk() 
menubar = tkinter.Menu(root)
root.config(menu=menubar)
model_menu = tkinter.Menu(menubar)
menubar.add_cascade(label="Model", menu=model_menu)
model_menu.add_command(label="Run model", command=run, state="normal") 

w = tkinter.Canvas(root, width=200, height=200)
w.pack()
w.create_rectangle(0, 0, 200, 200, fill="blue")


tkinter.mainloop()