matplotlib · QuLogic · Nov 12, 2016 · Nov 11, 2016
diff --git a/lib/matplotlib/backends/backend_tkagg.py b/lib/matplotlib/backends/backend_tkagg.py
@@ -750,6 +750,12 @@ def _Button(self, text, file, command, extension='.gif'):
        b.pack(side=Tk.LEFT)
        return b

+    def _Spacer(self):
+        # Buttons are 30px high, so make this 26px tall with padding to center it
+        s = Tk.Frame(master=self, height=26, relief=Tk.RIDGE, pady=2, bg="DarkGray")
+        s.pack(side=Tk.LEFT, padx=5)
+        return s
+
    def _init_toolbar(self):
        xmin, xmax = self.canvas.figure.bbox.intervalx
        height, width = 50, xmax-xmin
@@ -761,8 +767,8 @@ def _init_toolbar(self):

        for text, tooltip_text, image_file, callback in self.toolitems:
            if text is None:
-                # spacer, unhandled in Tk
-                pass
+                # Add a spacer -- we don't need to use the return value for anything
+                self._Spacer()
            else:
                button = self._Button(text=text, file=image_file,
                                   command=getattr(self, callback))