a tkinter (ttk) button extension that repeatedly invokes the command whilst the button is held down, includes a simple exponential acceleration

RepeatButton.py

from Tkinter import *
from ttk import *
class RepeatButton(Button):
	def __init__(self, _, **kw):
		Button.__init__(self, _)
		self.config(**kw)
		self.bind('<Button-1>', self._start)
		self.bind('<ButtonRelease-1>', self._end)
	def _start(self, event):
		self._delay = 1500
		self._on = True
		self._do()
	def _do(self):
		if self._on:
			self.invoke()
			if self._delay > 100:
				self._delay /= 2
			self.after(self._delay, self._do)
	def _end(self, event):
		self._on = False