title: Set style for Checkbutton or Labelframe in python tkinter
body: <p>I have designed a GUI using python tkinter. And now I want to set style for Checkbutton and Labelframe, such as the font, the color .etc
  I have read some answers on the topics of tkinter style, and I have used the following method to set style for both Checkbutton and Labelframe. 
  But they don't actually work.</p>
  
  <pre><code>Root = tkinter.Tk()
  ttk.Style().configure('Font.TLabelframe', font="15", foreground = "red")
  LabelFrame = ttk.Labelframe(Root, text = "Test", style = "Font.TLabelframe")
  LabelFrame .pack( anchor = "w", ipadx = 10, ipady = 5, padx = 10, pady = 0, side = "top")
  </code></pre>
  
  <p>Can you tell me the reasons, or do you have some other valid methods? Thank you very much!</p>