Sorry for the noob question but I really don't understand this.

I'm using python / tkinter and I want to display something (say, a canvas with a few shapes on it), and keep it displayed until the program quits. I understand that no widgets would be displayed until I call tkinter.tk.mainloop(). However, if I call tkinter.tk.mainloop(), I won't be able to do anything else until the user closes the main window.

I don't need to monitor any user input events, just display some stuff. What's a good way to do this without giving up control to mainloop?

EDIT:

Is this sample code reasonable:

class App(tk.Tk):
  def __init__(self, sim):
    self.sim = sim # link to the simulation instance
    self.loop()

  def loop():
    self.redraw() # update all the GUI to reflect new simulation state
    sim.next_step() # advance simulation another step
    self.after(0, self.loop)

  def redraw():
    # get whatever we need from self.sim, and put it on the screen

EDIT2 (added after_idle):

class App(tk.Tk):
  def __init__(self, sim):
    self.sim = sim # link to the simulation instance
    self.after_idle(self.preloop)

  def preloop():
    self.after(0, self.loop)

  def loop():
    self.redraw() # update all the GUI to reflect new simulation state
    sim.next_step() # advance simulation another step
    self.after_idle(self.preloop)

  def redraw():
    # get whatever we need from self.sim, and put it on the screen