matplotlib toolbar does not work in tkinter gui

Question

I wanna control my plot embedded in a tkinter gui with a navigationtoolbar

here my code:

import matplotlib
matplotlib.use("tkagg")
import matplotlib.pyplot as plt
from matplotlib.backends.backend_tkagg import figureCanvasTkAgg, NavigationToolbar2TkAgg

class Application(tk.Frame):

   def __init__(self, master=None):
       fig=plt.figure()
       ax=fig.add_axes([0.1,0.1,0.8,0.8],polar=True)
       tk.Frame.__init__(self,master)
       toolbar_frame=tk.Frame(root)
       toolbar_frame.grid(row=50, column=1)
       canvas=FigureCanvasTkAgg(fig,master=root)
       canvas.get_tk_widget().grid(row=0, column=1)
       canvas.show()
       toolbar=NavigationToolbar2TkAgg(canvas,toolbar_frame)
       toolbar.update()

   def plot(self):
      ax.plot(some data)
      canvas.show()
      ax.clear()
      #set axes
      root.after(10,self.plot)

A button calls the plot function for the first time, but i guess this is not important at this place. The data is plotted every 10ms in the polar plot in the GUI. This works fine. When I stop the loop, I wanna work with the current data in the polar plot. I see the navigationbar and can click on the buttons. But if I select for example the zoom rectangle item nothing happens. If I click the home button or the next or previous button all my data points get wiped out.

So someone an idea how to handle it?

Thanks!