On windows, new patch gives this:
Traceback (most recent call last):
  File "F:\Python\dev\4\py34\Lib\turtledemo\__main__.py", line 295, in <module>
    demo = DemoWindow()
  File "F:\Python\dev\4\py34\Lib\turtledemo\__main__.py", line 73, in __init__
    graph_frame = self.makeGraphFrame(pane)
  File "F:\Python\dev\4\py34\Lib\turtledemo\__main__.py", line 115, in makeGraphFrame
    self._makeBindings(turtle._Screen._canvas._rootwindow)
  File "F:\Python\dev\4\py34\Lib\turtledemo\__main__.py", line 130, in _makeBindings
    root_window.bind_all('<%s-minus>' % shortcut, self._decreaseFont)
  File "F:\Python\dev\4\py34\lib\tkinter\__init__.py", line 1049, in bind_all
    return self._bind(('bind', 'all'), sequence, func, add, 0)
  File "F:\Python\dev\4\py34\lib\tkinter\__init__.py", line 992, in _bind
    self.tk.call(what + (sequence, cmd))
_tkinter.TclError: bad event type or keysym "Ctrl"

/Ctrl/Control in "shortcut = 'Control" and demo runs.

        root_window.bind_all('<%s-minus>' % shortcut, self._decreaseFont)
        root_window.bind_all('<%s-=>' % shortcut, self._increaseFont)

^- shrinks on -_ key and num keypad.
&+ enlarges on =+ key but not num keypad.  Fix by adding
        root_window.bind_all('<%s-plus>' % shortcut, self._increaseFont)

^wheel either way maked giant type -- evt.delta on my machine is +-120!
        self.txtfont['size'] += evt.delta // 120
works like expected. And please spell out 'event'. 

Out general policy is one patch per issue. The one for #21587 already fixes two issues. After we finish that (see questions), produce a small patch for this.