I am using openerp7 for our client project. I am at intial stage now. I am having a doubt which files i should not touch to customize.

When i upgrade from openerp7 to odoo(8 version), which files will override.

Simple Task i am doing now, removing upgrade(announcement) bar at the top of the inner pages.

For this there are two ways i found,

1) Commenting animations.xml line in /addons/mail/__openerp__.py

2) Creating a custom module, that has css file which makes annoucement_bar class as visibility:hidden 

The solution one is perfect for me, because it will never add to the html.

The solution two has the provision for user to make it show using firebug/ console.

Please reply.