title: Centering and size a windows frame in Tkinter class python
body: <p>I want to center a window frame ad set a size using a ratio according to screensize. But I cannot see where to modify my code correctly to perform such program. My program is the following example :</p>
  
  <pre><code>class App:
      def __init__(self,master):
          ScreenSizeX = master.winfo_screenwidth()  # Get screen width [pixels]
          ScreenSizeY = master.winfo_screenheight() # Get screen height [pixels]
          ScreenRatio = 0.8                              # Set the screen ratio for width and height
          FrameSizeX  = int(ScreenSizeX * ScreenRatio)
          FrameSizeY  = int(ScreenSizeY * ScreenRatio)
          FramePosX   = (ScreenSizeX - FrameSizeX)/2 # Find left and up border of window
          FramePosY   = (ScreenSizeY - FrameSizeY)/2
  
          print FrameSizeX,FrameSizeY,FramePosX,FramePosY
  
          #geometry(str(self.winfo_screenwidth())+"x"+str(self.winfo_screenheight())+"+0+0")
          frame = Tkinter.Frame(master)
          frame.pack()
  
          self.button = Tkinter.Button(frame,text="Quit",fg="red",command=frame.quit)
          self.button.pack()
  
          self.hi_there = Tkinter.Button(frame,text="Hi!",command=self.say_hi)
          self.hi_there.pack()
  
      def say_hi(self):
          print "hello !"
  
  if __name__ == "__main__":
      root = Tkinter.Tk()
      app = App(root)
      root.mainloop()
  </code></pre>