What files change with an upgrade?

[Lpeek]

I know it's a very vague question, but I just wondered what files actually change with an upgrade? Is it documented anywhere?

Basically, I have just finished theming 2 custom stores 2 weeks ago, and then a new version gets released and I get the 'new version available' link appear when I log on to my store's backoffice. I really want to upgrade because it says its fixed some security issues, and I don't want an unsecure shop! But do I have to completely re-theme the shop? or are themes from prestashop 1.2.* compatible with the new 1.3.* ? Or is it just better for me to go into the code and remove the line that displays the 'new version available' when I log in?

Also some modules had to be changed in order for the theme to display how I want, I understand I'd more than likely need to re-code the modules in the new version to my needs? I can't just copy & paste the old files?

Thanks!

[rocky]

Yes, PrestaShop v1.2 themes work in PrestaShop v1.3, but you'll be missing out on all the bug fixes and improvements that have been made in PrestaShop v1.3. There is no list of all the files that were changed, since most files have been changed. It is best to remodify the default PrestaShop v1.3.1 theme and modules, but if you don't want to do that, you should at least manually apply the security fixes outlined here.