little fixes, add msg_window()

function for Messagebox to show a tk.Toplevel()
replace var = open() with:
with open() as var:
and remove by classes (tk.tk) and super()

start_wg.py

@@ -1,12 +1,9 @@
 #!/usr/bin/python3
 from subprocess import check_call
 
-
 path_to_file = '/home/punix/.config/wire_py/wg_py'
 
-
-with open(path_to_file, ) as file:
-    for line in file.readlines():    
-        a_con = line[5:]             
+with open(path_to_file, 'r') as file:
+    *_, line = file
+a_con = line[5:]
 check_call(['nmcli', 'connection', 'up', a_con])
-file.close()