Extract a base app to deal with main_window layouts

base.py

@@ -0,0 +1,19 @@
+import tkinter
+
+class BaseApp(tkinter.Tk):
+	# This is the base app which create center tkinter layouts
+	# To reuse it, make it inherited by other app files
+	def __init__(self, title, width, height):
+		super(BaseApp, self).__init__()
+		self.title(title)
+		self.__geometry(width, height)
+
+	def __geometry(self, width, height):
+		# put window in the center of the screen
+		offset_width = (self.winfo_screenwidth() - width) // 5 * 2
+		offset_height = (self.winfo_screenheight() - height) // 5 * 2
+		self.geometry("%sx%s+%s+%s" % (width, height, offset_width, offset_height))
+
+if __name__ == '__main__':
+	app = BaseApp('hello', 400, 300)
+	app.mainloop()

config.py

@@ -4,16 +4,15 @@
 import tkinter.filedialog
 import tkinter.messagebox
 from model import loader
+from base import BaseApp
 
 class ConfigApp(object):
 	# GUI for the config app.
 	# Need to be called before login and query.
 
 	def __init__(self):
 		# Initialization for the GUI. All of the variables are private here.
-		self.__main_window = tkinter.Tk()
-		self.__main_window.title("Configurations")
-		self.__set__geometry(400, 150)
+		self.__main_window = BaseApp("Configurations", 400, 150)
 		self.__status = False
 
 		self.__ID = ''
@@ -41,12 +40,6 @@ def __init__(self):
 
 		self.__main_window.mainloop()
 
-	def __set__geometry(self, width, height):
-		# put window in the center of the screen
-		offset_width = (self.__main_window.winfo_screenwidth() - width) // 5 * 2
-		offset_height = (self.__main_window.winfo_screenheight() - height) // 5 * 2
-		self.__main_window.geometry("%sx%s+%s+%s" % (width, height, offset_width, offset_height))
-
 	def __load_model(self, model_category, filetypes, loader):
 		# generic model loader, filetypes work as a filter, loader is a function
 		model_category = model_category.lower()

result.py

@@ -1,13 +1,12 @@
 import tkinter
 import tkinter.ttk
+from base import BaseApp
 from course import score
 
 class ResultApp(object):
 	def __init__(self, score_table):
 		# This app should be utilized to show score results
-		self.__main_window = tkinter.Tk()
-		self.__main_window.title("Query Results")
-		self.__set__geometry(800, 600)
+		self.__main_window = BaseApp("Query Results", 800, 600)
 		self.__score_frame = tkinter.Frame(self.__main_window)
 
 		# Information