Change button color on if clause - Tkinter

[indeed]

Hi guys,
I'm new to Python, and now I'm trying to make a simple GUI with Tkinter.

So.. I want to change a button's color based on if file is selected clause:

import Tkinter, tkFileDialog, Tkconstants 
from Tkinter import * 

version = '1.0'
filetext= 'Select Landsat 8 OLI'
def openFile():
    filename = tkFileDialog.askopenfilename(parent=root,initialdir='/home/',title=filetext ,filetypes=[('ERDAS IMAGINE', '.img')]) ## filename not filehandle
    filebut["text"]= str(filename) if filename else filetext

root = Tk() 
root.title('NDVI GUI ' + version)
root.geometry('300x100')
#Options for buttons
button_opt = {'fill': Tkconstants.BOTH, 'padx': 5, 'pady': 5}

#Define asking watermark file button
filebut = Button(root, text = filetext, fg = 'black', command= openFile)
filebut
filebut.pack(**button_opt)
root.mainloop()

I was wondering if I could change bg to green of the

filebut = Button

based on the function

openFile

clause

if filename else filetext

Something like if filename == None:
bg = "green"
else pass

I know that I probably this is very bad written but just wanted to see if could be done. Thank you!

[dwblas]

To change any widget's color, including a button, you use the config function with a "background " or foreground" parameter, some_button.con fig(background= "green"), or access the dictionary directly, some_button["background "]="green" http://effbot.org/tkinterbook/button.htm

[indeed]

Thank you, I found that link myself. But I can't make it work..
What I want to do is to change button bg color when a condition is met. If file is selected change to green, if not don't (pass).