Backport PR #15266: Embedding in Tk example: Fix toolbar being clipped.

jmehne · MeeseeksDev[bot] · commit af4648987d4d · 2019-09-15T12:58:35.000Z
diff --git a/examples/user_interfaces/embedding_in_tk_sgskip.py b/examples/user_interfaces/embedding_in_tk_sgskip.py
@@ -25,11 +25,9 @@
 
 canvas = FigureCanvasTkAgg(fig, master=root)  # A tk.DrawingArea.
 canvas.draw()
-canvas.get_tk_widget().pack(side=tkinter.TOP, fill=tkinter.BOTH, expand=1)
 
 toolbar = NavigationToolbar2Tk(canvas, root)
 toolbar.update()
-canvas.get_tk_widget().pack(side=tkinter.TOP, fill=tkinter.BOTH, expand=1)
 
 
 def on_key_press(event):
@@ -40,6 +38,12 @@ def on_key_press(event):
 canvas.mpl_connect("key_press_event", on_key_press)
 
 button = tkinter.Button(master=root, text="Quit", command=root.quit)
+
+# Packing order is important. Widgets are processed sequentially and if there
+# is no space left, because the window is too small, they are not displayed.
+# The canvas is rather flexible in its size, so we pack it last which makes
+# sure the UI controls are displayed as long as possible.
 button.pack(side=tkinter.BOTTOM)
+canvas.get_tk_widget().pack(side=tkinter.TOP, fill=tkinter.BOTH, expand=1)
 
 tkinter.mainloop()
