ListedSubWindow: Switch to logging.

src/View/ListedSubWindow.py

 # -*- coding: utf-8 -*-
 
+import logging
 from functools import reduce
 
+logger = logging.getLogger()
+
 class ListedSubWindow(object):
     def __init__(self):
         super(ListedSubWindow, self).__init__()
@@ -17,7 +20,7 @@ class ListedSubWindow(object):
     def sub_win_add(self, name, win):
         self.sub_win_list.append((name, win))
         self.sub_win_cnt += 1
-        print(f"+ {name} ({self.sub_win_cnt})")
+        logger.info(f"Open window: {name} ({self.sub_win_cnt})")
 
     def sub_win_del(self, name):
         self.sub_win_list = list(
@@ -27,7 +30,7 @@ class ListedSubWindow(object):
             )
         )
         self.sub_win_cnt = len(self.sub_win_list)
-        print(f"- {name} ({self.sub_win_cnt})")
+        logger.info(f"Close window: {name} ({self.sub_win_cnt})")
 
     def sub_win_exists(self, name):
         return reduce(