diff --git a/src/gui/mainwindow.py b/src/gui/mainwindow.py
--- a/src/gui/mainwindow.py
+++ b/src/gui/mainwindow.py
@@ -1,18 +1,17 @@
 import tkinter as tk
 from tkinter import N,S,E,W
 
-from .util import MsgMixin
 from .menu import MainMenu
 from .boardview import BoardView
 from .imgview import ImgView
 from .statusbar import StatusBar
 
 
-class MainWindow(tk.Frame,MsgMixin):
-	def __init__(self,parent,master=None):
+class MainWindow(tk.Frame):
+	def __init__(self,parent):
 		self.parent=parent
 
-		tk.Frame.__init__(self, master)
+		tk.Frame.__init__(self, parent.root)
 		self.grid(column=0,row=0,sticky=(N,S,E,W))
 		self._createWidgets()
 
@@ -22,11 +21,11 @@ class MainWindow(tk.Frame,MsgMixin):
 	def _createWidgets(self):
 		# menu
 		self.parent.root.option_add('*tearOff',False)
-		self._menu=MainMenu(self.parent,self.parent.root)
+		self._menu=MainMenu(self.parent)
 
 		# a captured frame with overlay graphics
 		self._imgWrapper=tk.Frame(self,width=480,height=360)
-		self.imgView=ImgView(self._imgWrapper,self)
+		self.imgView=ImgView(self.parent,self._imgWrapper)
 
 		self._imgWrapper.grid(column=0,row=0,sticky=(N,S,E,W))