matplotlib · tacaswell · Aug 11, 2020 · Jun 28, 2020 · Jun 28, 2020 · Jun 28, 2020
diff --git a/lib/matplotlib/backends/_backend_tk.py b/lib/matplotlib/backends/_backend_tk.py
@@ -209,7 +209,6 @@ def __init__(self, figure, master=None, resize_callback=None):
         # to the window and filter.
         def filter_destroy(event):
             if event.widget is self._tkcanvas:
-                self._master.update_idletasks()
                 self.close_event()
         root.bind("<Destroy>", filter_destroy, "+")
 
@@ -233,7 +232,6 @@ def resize(self, event):
         self._tkcanvas.create_image(
             int(width / 2), int(height / 2), image=self._tkphoto)
         self.resize_event()
-        self.draw()
 
     def draw_idle(self):
         # docstring inherited
@@ -383,6 +381,16 @@ def flush_events(self):
         # docstring inherited
         self._master.update()
 
+    def start_event_loop(self, timeout=0):
+        # docstring inherited
+        if timeout > 0:
+            self._master.after(int(1000*timeout), self.stop_event_loop)
+        self._master.mainloop()
+
+    def stop_event_loop(self):
+        # docstring inherited
+        self._master.quit()
+
 
 class FigureManagerTk(FigureManagerBase):
     """
@@ -527,10 +535,6 @@ def __init__(self, canvas, window, *, pack_toolbar=True):
         if pack_toolbar:
             self.pack(side=tk.BOTTOM, fill=tk.X)
 
-    def destroy(self, *args):
-        del self.message
-        tk.Frame.destroy(self, *args)
-
     def set_message(self, s):
         self.message.set(s)
 
@@ -554,8 +558,6 @@ def set_cursor(self, cursor):
             window.configure(cursor=cursord[cursor])
         except tkinter.TclError:
             pass
-        else:
-            window.update_idletasks()
 
     def _Button(self, text, image_file, toggle, command):
         image = (tk.PhotoImage(master=self, file=image_file)

diff --git a/lib/matplotlib/backends/backend_tkagg.py b/lib/matplotlib/backends/backend_tkagg.py
@@ -8,12 +8,10 @@ class FigureCanvasTkAgg(FigureCanvasAgg, FigureCanvasTk):
     def draw(self):
         super().draw()
         _backend_tk.blit(self._tkphoto, self.renderer._renderer, (0, 1, 2, 3))
-        self._master.update_idletasks()
 
     def blit(self, bbox=None):
         _backend_tk.blit(
             self._tkphoto, self.renderer._renderer, (0, 1, 2, 3), bbox=bbox)
-        self._master.update_idletasks()
 
 
 @_BackendTk.export

diff --git a/lib/matplotlib/backends/backend_tkcairo.py b/lib/matplotlib/backends/backend_tkcairo.py
@@ -23,7 +23,6 @@ def draw(self):
         _backend_tk.blit(
             self._tkphoto, buf,
             (2, 1, 0, 3) if sys.byteorder == "little" else (1, 2, 3, 0))
-        self._master.update_idletasks()
 
 
 @_BackendTk.export

diff --git a/lib/matplotlib/tests/test_backends_interactive.py b/lib/matplotlib/tests/test_backends_interactive.py
@@ -194,3 +194,32 @@ def test_webagg():
     conn.close()
     proc.send_signal(signal.SIGINT)
     assert proc.wait(timeout=_test_timeout) == 0
+
+
+@pytest.mark.backend('TkAgg', skip_on_importerror=True)
+def test_never_update(monkeypatch, capsys):
+    import tkinter
+    monkeypatch.delattr(tkinter.Misc, 'update')
+    monkeypatch.delattr(tkinter.Misc, 'update_idletasks')
+
+    import matplotlib.pyplot as plt
+    fig = plt.figure()
+    plt.show(block=False)
+
+    # regression test on FigureCanvasTkAgg
+    plt.draw()
+    # regression test on NavigationToolbar2Tk
+    fig.canvas.toolbar.configure_subplots()
+
+    # check for update() or update_idletasks() in the event queue
+    # functionally equivalent to tkinter.Misc.update
+    # must pause >= 1 ms to process tcl idle events plus
+    # extra time to avoid flaky tests on slow systems
+    plt.pause(0.1)
+
+    # regression test on FigureCanvasTk filter_destroy callback
+    plt.close(fig)
+
+    # test framework doesn't see tkinter callback exceptions normally
+    # see tkinter.Misc.report_callback_exception
+    assert "Exception in Tkinter callback" not in capsys.readouterr().err