How to make a button flashing?

[Peter Otten]

huey.y.jiang at gmail.com wrote:

> Hi All,
> 
> I forgot the syntax of making a button flash, and failed to find an
> example in the web. I use Tkinter, to create a button. Then made it
> packed, and showed up. Now I am trying to make button b flashing, to make
> it get better noticed. I checked the docs, and found a method flash() is
> available, then I tried:
> 
> b.flash()
> 
> there was no error message popped out, but there was nothing happened
> also. I wonder who can give me this help? Thanks!
> 
> Huey

Quoting http://tcl.tk/man/tcl8.6/TkCmd/button.htm#M16

"""
pathName flash
    Flash the button. This is accomplished by redisplaying the button 
several times, alternating between the configured activebackground and 
background colors. At the end of the flash the button is left in the same 
normal/active state as when the command was invoked. This command is ignored 
if the button's state is disabled.
"""

So to see something you have to ensure that the two background colors 
actually differ. Complete example:

import tkinter as tk
root = tk.Tk()

button = tk.Button(root, text="Hello")
button.pack()

button["activebackground"] = "red"
button["background"] = "silver"

root.after(1000, button.flash)
root.mainloop()